HP 3048A Service manual

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Page 1

Errata

Title & Document Type: 3048A Phase Noise Measurement System Calibration Manual

Manual Part Number: 03048-90015

Revision Date: June 1990

HP References in this Manual

This manual may contain references to HP or Hewlett-Packard. Please note that HewlettPackard's former test and measurement, semiconductor products and chemical analysis businesses are now part of Agilent Technologies. We have made no changes to this manual copy. The HP XXXX referred to in this document is now the Agilent XXXX. For example, model number HP8648A is now model number Agilent 8648A.

About this Manual

We’ve added this manual to the Agilent website in an effort to help you support your product. This manual provides the best information we could find. It may be incomplete or contain dated information, and the scan quality may not be ideal. If we find a better copy in the future, we will add it to the Agilent website.

Support for Your Product

Agilent no longer sells or supports this product. You will find any other available product information on the Agilent Test & Measurement website:

www.tm.agilent.com

Search for the model number of this product, and the resulting product page will guide you to any available information. Our service centers may be able to perform calibration if no repair parts are needed, but no other support from Agilent is available.

Page 2

SYSTEM CALIBRATION MANUAL

HP 3048A

PHASE NOISE

MEASUREMENT

SYSTEM

June 1990

03048-90015 "

WL"~^

HEWLETT

*■*■« ■ i^ww^^i

PACKARD

■

Page 3

HP3048A

PHASE NOISE MEASUREMENT SYSTEM

(Including Options 001,

Calibration Manual

This manual applies directly number:

HP 3048A Software Version: REV: A.02.00

"This material U.S.

Government pursuant to the Copyright License

under the clause

EAST 24001 MISSION AVENUE, TAF C-34, SPOKANE, WASHINGTON,

Calibration Manual

Part 03048-90015

002, 003, 004,

SERIAL NUMBERS

software version

rev.25MAY90

Third Edition

may be

reproduced

DFARS 52.227-7013 (APR 1988)"

by or for the

005,

U.S.A.

and 006)

99220

Other Documents Availiable: Microfiche Calibration Manual Operation Manual Microfiche Operation Manual Reference Manual Microfiche Reference Manual HP 11848A Service Manual Microfiche HP 3048A System Software Discs,HP Part 03048-90018 HP 3048A Quick Reference Guide 03048-90019

11848A Service Manual

Part 03048-90016

Part 03048-90001

Part 03048-90014

Part 03048-90002

Part 03048-90017

Part 11848-90004

Part 11848-90012

Printed

U.S.A. : June

HEWLETT

PACKARD

1990

Page 4

SAFETY CONSIDERATIONS

GENERAL

This product and related documentation must be reviewed for familiarization with safety markings and instructions before operation.

This product is a Safety Class I instrument (provided with a protective earth terminal).

BEFORE APPLYING POWER

Verify that the product is set to match the available line voltage and the correct fuse is installed.

SAFETY EARTH GROUND

An uninterruptible safety earth ground must be provided from the main power source to the product input wiring terminals, power cord, or supplied power cord set.

SAFETY SYMBOLS

marked with this symbol when it is necessary for the user to refer to the instruction manual (refer to Table of Contents.)

Instruction manual symbol: the product will be

WARNING

Any interruption of the protective (grounding)

conductor (inside or outside the instrument) or disconnecting the protective earth terminal will cause a potential shock hazard that could resulting personal injury. (Grounding one conductor of a two conductor outlet is not sufficient

protection).

Whenever it is been impaired, the instrument must be made. inoperative and be secured against any uhin-; tended operation.

If this instrument is to be energized via an autotransformer (for voltage reduction) make sure the common terminal is connected to the earth terminal of the power source.

Servicing instructions are for use by service

trained personnel

tric shock, do not perform any servicing unless qualified to do so.

likely ■

only.

that the protection has;

To avoid dangerous elec-

Indicates hazardous voltages.

— Indicates earth (ground) terminal.

WARNING

It calls attention to a procedure, practice, or the like, which, if not correctly performed or adhered to, could result in personal injury. Do not proceed beyond a WARNING sign until the indicated conditions are

fully understood and met.

CAUTION calls attention to an operating procedure, practice, or the like, which, if not correctly performed or adhered to,

could result in damage to or destruction of part

or all of the product. Do not proceed beyond a

CAUTION sign until the indicated conditions are fully

understood and met.

The WARNING sign denotes a hazard.

The

CAUTIO

N sign denotes a hazard. It

Adjustments described in the manual are performed with power supplied to the instrument

while protective covers are removed. Energy

available

in personal injury.

Capacitors inside the instrument may still be charged even if the instrument has been disconnected from its source os supply.

For continued protection against fire place the line fuse(s) only with 250V fuse(s) of

the same current rating and type (for exam-

ple, normal blow, time delay, etc.) Do not use

repaired fuses or short circuited fuseholders.

at may points may, if contacted, result

hazard,

re-

Page 5

ATTENTION

Static Sensitive

Devices

This instrument was constructed in an ESD (electro-static discharge)

protected environment. This is because most of the semi-conductor

devices used in this instrument are susceptible to damage by static

discharge. Depending on the magnitude of the charge, device substrates can be

punctured or destroyed by contact or mere proximity of a static charge.

The results can cause degradation of device performance, early failure, or immediate destruction.

These charges are generated in numerous ways such as simple contact, separation of materials, and normal motions of persons working with static sensitive devices.

When handling or servicing equipment containing static sensitive devices, adequate precautions must be taken to prevent device damage or destruction.

Only those who are thoroughly familiar with industry accepted techniques for handling static sensitive devices should attempt to service circuitry with these devices.

In all instances, measures must be taken to prevent static charge build-up on work surfaces and persons handling the devices.

Page 6

Model 3048A Table of Contents

TABLE OF CONTENTS

General Information 1 Quick Check 5 Spur Accuracy Test 7 Noise Flatness Test 11 Noise Floor Test 14 Microwave Phase Detector Conversion Loss (Option 201) Test 16 Functional Tests 19 DAC Tests 21 A3 Adjustments 23 A4 Adjustments 29 Option 1 Calibration 37 Option 2 Calibration 40 Internal Sources Calibration 46 Spectral Purity Tests for Options 001 and 002 49 Spectral Purity Tests for Options 003 and 004 51 Spectral Purity Tests for Options 005 and 006 55 Appendix A: Block Diagram and System Troubleshooting : A-l Appendix B: HP 8662A or HP 8663A 640 MHz Spectral Purity Test B-l

Page 7

Model 3048A

INTRODUCTION

This manual documents the procedures which calibrate the HP 3048A Phase Noise Measurement System. System calibration assures that the System meets its published specifications. The procedures consist of system checks, adjustments, performance tests, and signal path characterization.

Calibration of the HP 11848A Phase Noise Measurement Interface results from calibration of the System.

iter

The need for calibration is governed by the situation. It is usually not necessary nor even desirable to recalibrate the System frequently. Testing guidelines are summarized below. ^

General Information

NOTE

"Calibration" as referred to in this manual should not be confused with the measurement calibration referred to in the normal course of making a phase noise measurement. Measurement calibration surement with phase as the

detector

and determination of

lock) refers to

constant,

the

characterization

tuning sensitivity of the signal

phase lock loop bandwidth.

(especially,

of such parameters

source's

a mea-

FM input,

Calibration

Most tests are automatic. Operator intervention is documented in the System's test software. It is recommended, however, that the user follow along in this manual as the tests are running.

EQUIPMENT REQUIRED

Equipment required, but not part of the System, is minimal. A feature of the System is the four sources built into the Interface which substitute for external sources in many cases.

Extensive use is made of the HP 3561A Dynamic Signal Analyzer both as a signal source (using its built-in noise source) and as a signal analyzer. Any calibrated HP 3561A can be used in calibrating the System; it does not need to be the specific HP 3561A in the System.

The external test equipment requirements are given in Table 1.

PERFORMANCE TEST RECORD

Most test results can be hardcopied on the System's printer. This practice is recommended. It is

also recommended that the serial number of the Interface under test be recorded in the System Configuration Table so that it will appear on the printouts.

rev. 29MA Y90 General Information

Page 8

Calibration Model 3048A

Table 1. Recommended Test Equipment

Instrument

Type

Frequency

Frequency Range: 10 to 550 MHz

Critical Specifications

HP5315A

Counter

Microwave

Sources

For systems with Option 201 only Frequency Range: 1.2 to 18 GHz

(1)

; 2 required

See note (2).

Maximum Level: >+7 dBm (source 1), >0 dBm (source 2)

Stability: drift small compared to 100 kHz

Noise Floor Test Fixture

Power Meter and Sensor

Printer

(1)

Option

201

adds the 1.2 to 18 GHz input.

^2' A variety of combinations of sources with adequate output and frequency range can be used for this test.

Supplied with system. No substitute recommended.

For systems with Option 201 only Frequency Range: 1.2 to 18 GHz Level Range: >+7 dBm

HP-IB;

graphics; usually part of the System

(2)

HP 11848-61032

HP 435B HP 8481A

HP ThinkJet

Suggested

Model

Table 2. Performance

Verification

Guideline

Check or Test to Run

Situation'1)

New Installation Annual Calibration

Quick

Check

Performance

Tests

<3)

Functional

tests

(3)

DAC

Tests

(3)

Option 1 X Option 2

Ambient Change Confidence Check HP 11848A Repair HP 3561A Repair

x<a>

(3)

W Perform the Adjustments when recommended by the other tests.

(2)

Run the Performance Tests when it is desired to ensure that the System meets its published specifications.

(3) Perform these in the following

order:

Functional Tests, DAC Tests, Option 2 Calibration, Internal Sources Calibration, then

Performance Tests.

Calibration

(3)

Sources

(3)

2 General Information

Page 9

Model 3048A Calibration

WHEN AND WHAT TO TEST

Use Table 2 as a guideline for verifying the performance of the System. The checks and tests are summarized below. The procedures are listed in the order in which they are

described except for the Source Options Spectral Purity Tests which follow the Adjustments. Quick Check is a confidence check which performs a complete phase-locked measurement of the phase

noise of the 10 MHz A vs. B internal sources. Performance Tests verify that the System meets its published specifications. The tests are as follows:

Spur Accuracy Test verifies the accuracy of noise measurements by measuring the level of phase modulation on a carrier with a known discrete sideband level. (In the context of phase noise measurements, discrete sidebands are often referred to as spurious signals or "spurs".)

Noise Flatness Test measures the unflatness of

test needs to be performed only when an RF spectrum analyzer is in the System's Configuration Table.

Noise Floor Test verifies the measurement sensitivity.

Microwave Phase Detector Conversion Loss (Option 201) Test measures the conversion loss of

the 1.2 to 18 GHz phase detector. If the detector is not within specification, the noise floor will be degraded when the detector is used. (Option 201 adds the 1.2 to 18 GHz input to the Interface.)

Source Options Spectral Purity Tests verify the contribution of optional sources to the noise

floor. (The procedures for these tests follow the Adjustments.)

Functional Tests verify the functionality of the HP 11848A Phase Noise Interface. The tests measure

the paths for proper switching, DC offsets, amplifier gains, filter responses, etc. (Adjustments to the

HP 11848A can be made when Functional Tests show a problem.) DAC Tests verify the accuracy of the three DACs in the HP 11848A Phase Noise Interface.

(Adjustments to the DACs should be made if a DAC is out of limits.) The DAC Tests require accessing

the interior of the Interface. Option 1 Calibration totally characterizes the HP 11848A measurement paths and generates new

calibration data. The data collected replaces the data generated during the previous calibration. The new data may be stored in mass storage. (However, it does not replace the extra data obtained from the Option 2 Calibration.)

noise

signals at offsets greater than 500 kHz. This

Option 2 Calibration is the same as Option 1 Calibration but includes the characterization of two additional reference paths.

Internal Sources Calibration determines and records as data the nominal DAC 2 and DAC 3 voltages (VNOMs) required to set the three tuneable, internal sources (VCOs) to their center frequencies.

Adjustments are made when other tests or checks indicate the need. Adjustments require accessing the interior of the Interface.

A3 Adjustments are made to the A3 Analyzer Interface Assembly.

A4 Adjustments are made to the A4 Phase Detector Assembly.

General Information 3

Page 10

Calibration

THE IMPORTANCE OF SYSTEM CALIBRATION DATA

Phase noise measurements are ultimately made by the HP 3561A Dynamic Signal Analyzer after the ( demodulated "noise signal" has passed through the HP 11848A Phase Noise Interface. Phase lock loop control signals also pass through the Interface. The Interface conditions the signals for best measurement sensitivity and accuracy. It is therefore important to know the characteristics of the circuits in the Interface.

The Interface's characteristics are acquired during the Option 1, Option 2, and Internal Sources Calibrations that are described above. The acquired data is stored on the mass-storage media (hard or floppy disc). During the normal course of operation, the System loads the data into the computer's memory (RAM) where it is accessed by the program as needed to correct the raw measurement data. Therefore, the stored data must match the specific Interface being used. It is a good practice to keep the Interface's serial number in the System's Configuration Table which will then appear on data printouts.

The calibration data is stored in two data files: "CALDATALO" and "CALDATAHI". CALDATALO is used for signal-path circuits through 100 kHz. CALDATAHI is used for signal paths above 100 kHz plus the VNOMs (the nominal tuning voltage of the tuneable, internal sources) and noise-flatness data for flatness variations greater than 2 dB.

Model 3048A

General Information

Page 11

Model 3048A

DESCRIPTION

The Quick Check is a straight-forward, phase-lock-loop measurement of the phase noise of the two internal 10 MHz sources (A vs. B). Though the check is easy to run, a large portion of the circuitry in the HP 11848A Phase Noise Interface is exercised. A completed measurement with good results verifies that the System is operating correctly but does not verify its accuracy.

The check uses only equipment that is part of the System. Measurement definition parameters for this test are retrieved from a Test File named "DEFAULT".

PROCEDURE

Press the System Preset softkey. This softkey appears at the Main Software Level menu.

Quick Check

This

check

duplicates some of the guided tour in the Getting Started section

of the Operating Manual.

Calibration

NOTE

Press the

addresses each instrument listed in the System's Configuration Table. If an instrument does not respond to the HP-IB address listed for it, the System will inform you with a display message.

(For details on adding an instrument to the System's Configuration Table or verifying an HP-IB

address, refer to Setting Up the HP-IB Addresses in the installation section of the HP 3048A

Operating Manual.)

Connect the HP 3561A input and the two 10 MHz source outputs to the HP 11848A as shown

in the connect diagram on the computer display and in Figure 1. Note especially the rear-panel connections.

Press the Proceed softkey to run the test. The measurement should proceed without error

messages, and the measured noise results should be within 10 dB of that in Figure 2. (The plot in Figure 2 is typical for a System without an RF spectrum analyzer. The measurement takes about

10 minutes depending on the controller and the presence of the RF spectrum analyzer.)

New

Msrmnt softkey to initiate the measurement.

|Yes,

Proceedj softkey to indicate that new measurement data is desired. The System now

NOTE

The Interface's SPECTRUM ANALYZER output should either be terminated in

50Q

or an RF spectrum analyzer should be connected to it.

Quick Check 5

Page 12

Calibration

NOISE INPUT

FROM

3561A

SOURCE OUTPUT

(REAR PANEL)

HP 3561A DYNAMIC

SIGNAL ANALYZER

HP 11848A PHASE NOISE INTERFACE

3561A

INPUT

(CONNECT

SPECTRUM ANALYZER OR 50-OHM LOAD HEREO

SPECTRUM ANALYZER

Model 3048A

-10

-20

-30

-40

-50

-G0

-70

-80

-90

-100

-1 10

-120

-130

-140

-150

-160

-170

Qhp:

3048H Carrier

iii

^Y/u

^Hu

"""fc^

III

HP3048H

^ml

100

Figure

DEMO:

■: 10.E+6

1 1 il .

vvl

JU.

Quick Check Setup

10 MHz

III

ifl Jtdi

"R"

vs. 10 Mr

Dec 1987 16;

III

"B"

37:27 - 16:40:33

III

^ilL

111

IK 10K

Itf) CdBc/Hz: vs fCHz:

III

100K

6 Quick Check

Figure

Typical

Noise Plot for the System Quick

Check

Page 13

Model 3048A Calibration

Spur Accuracy Test

DESCRIPTION

In this test an external audio tone is input to the phase modulator of the internal 10 MHz B Oscillator to generate a 10 MHz carrier with discrete, phase-modulation sidebands. The sideband level (relative to the carrier) is calibrated with the HP 3561A Dynamic Signal Analyzer then measured as a normal phase noise measurement (with the 10 MHz A Oscillator phase locked to 10 MHz B Oscillator). The measurements are made with audio tones of 5.5, 55, 550, 5500, 55 000, and (if an RF spectrum analyzer is present) 550 000 Hz.

To calibrate the sideband level (relative to the carrier), the two 10 MHz Oscillators (A and B) are set 785 Hz apart and fed into the RF Phase Detector. The amplitude of the 785 Hz beatnote is measured by the HP 3561A. This level is the carrier reference level. Then the phase modulation sidebands for each modulation rate are measured with the HP 3561A and the relative sideband level is computed as the ratio of the two measurements.

The RF signal simulates the spurious discrete phase modulation (often called "spurs") frequently appearing in phase noise measurements. Although testing is done on discrete tone sidebands, the general accuracy of the noise sideband measurement is verified.

If an RF spectrum analyzer is not present, the test covers offsets of 1 Hz to 100 kHz. If an RF analyzer is present the range is 1 Hz to 1 MHz.

^EQUIPMENT

Printer. The test requires the presence of a printer in the System's Configuration Table.

Audio Source. The Spur Accuracy Test will run automatically if an HP 3325A Function Generator is

in the System's Configuration Table. If this function generator is not available, any manually controlled function generator or audio source having exact decade frequency switching covering 5 Hz to 55 kHz can be used. (The range must be 5 Hz to 550 kHz if an RF spectrum analyzer is configured in the

System.) The HP 3312A Function Generator is a typical manual audio source which can be used in this test. If no function generator is found in the system instrument configuration table, the software assumes you have only a manual audio source and you will be prompted for the proper settings.

PROCEDURE

NOTE

The flatness of the audio source must be better than ±0.3 dB when switching from 55 kHz to 550 kHz. The 550 kHz span is only used when an

RF spectrum analyzer is present.

Press the Spci. Funct'n softkey. This softkey appears at the Main Software Level menu.

Spur Accuracy Test 7

Page 14

Calibration Model 3048A

NOTE

troubleshoot

mode has been selected

(by

pressing the

you will be prompted for the setup diagram two times. Press the

Test Mode

softkey),

Proceed|

softkey after the second setup diagram is displayed.

Press the |3048A Sys

Press the

Press the |Spur

Press the

Perf. Tests

New Msrmnt

Chk|

softkey.

Accy.j

softkey. The System will then load the Spur Accuracy Test File.

softkey.

6. Connect the instruments as shown in the on-screen connection diagram and in Figure 3.

NOTE

If a function generator is to be under automatic figuration

Table

must

have

the

literal

name

control,

"FUNCT

the System's Con-

GEN"

and model "3325A".

The Interface's SPECTRUM ANALYZER output should either be termi-

nated in 500 or an RF spectrum analyzer should be connected to it.

Press the

Proceed

softkey. If the function generator is under automatic control, the measurement should proceed without error messages, and the measured spurs should be similar to the ones shown in Figure 4 with no failures listed. (The measurement takes about 10 minutes depending on controller and the presence of the RF spectrum analyzer.) If the function generator or audio source is under manual control, proceed with step 8.

AUDIO SOURCE

NOISE INPUT

FROM

3581A

SOURCE OUTPUT

(REAR PANEL)

TONE INPUT

(REAR PANEL)

Figure 3. Spur

HP 3561A DYNAMIC

SIGNAL ANALYZER

[o]

HP 11648A PHASE NOISE INTERFACE

Accuracy

Test Setup

5rM>

3S61A

INPUT (CONNECT

RF SPECTRUM ANALYZER

SPECTRUM ANALYZER

8 Spur Accuracy Test

Page 15

NOTE

Calibration

// an RF spectrum analyzer is not present, the test

covers

offsets of 1 Hz to

100 kHz. If an RF analyzer is present the range is 1 Hz to 1 MHz.

■IVWVVVVVIlMllVMlMVW

CAUTION

In the following step, do not apply more than

to the HP 11848A

peak

rear-panel TONE INPUT or the internal protection fuse may blow.

If the function generator or audio source is under manual control, set the initial level to 0.25V

(+1 dBm) into a 50O load as prompted by the display. Press the Proceed softkey to continue. Set the audio source to the first measurement frequency as prompted on the display and then set

the amplitude, as read on the HP 3561A Dynamic Signal Analyzer (FFT Analyzer), as prompted by the display. Press the Proceed softkey after completing each setting.

NOTE

Do not change the frequency vernier or amplitude setting of the audio source after these initial settings have been made. The frequency must be changed only by using decade switching of the audio source.

The test will pause after each frequency is measured and prompt for a new frequency setting. This will be done twice: once for calibrating the phase modulation and once for reading the

demodulated phase modulation. Press the

Proceed

softkey after completing each setting. When the measurement is complete, the measured spurs should be similar to the ones shown in Figure 4 with no failures listed.

NOTE

// this test fails, check the level of the calibration spur versus the measured spurs in the printed results to help determine what caused the failure.

After the Spur Accuracy Test has been run, two additional softkeys ( Recal Spurs and Repeat Msrmnt ) are

The

Recal Spurs softkey allows you to remeasure all spurs from 5.5 Hz to

available.

55 kHz. The Repeat Msrmnt| softkey allows you to repeat the measurement without

recalibrating the reference spurs. These additional softkeys allow you to repeat the measurement with the

same data as the original measurement, or to

recalibrate

the spurs and then

repeat the measurement.

Spur Accuracy Test 9

Page 16

Calibration Model 3048A

Dec 1987,

HP11848A

14:17:21

S/N

2621A00106

HP11848A SPUR ACCURACY PERFORMANCE TEST

TEST FREG)

(Hz.)

5.5 55 550

5.5E+3

55.E+3

Lhp] 3048R Carrier: 10.E+G

—i

1—i—r-i 1 1—i—i—i 1

CALIBRATED SPUR

LVL

(DBC)

60.3

60.19

- 60.29

- 60.24

- 60.08

HP3048R SPUR RCCURRCY PERFORMRNCE TEST

MEASURED SPUR

LVL

(DBC)

- 60.46

- 60.68

- 60.96

- 60.46

- 60.58

Hz 29 Dec 1987

1—i—I—I

SPECIFIED

ACCURACY

(+/-DB)

1 1—i—i—i 1 1—i—r

MEASURED ACCURACY

(DB)

0.16

0.49

0.67

0.22

0.5

14:12:25 - 14:17:18

PASS/ FAIL

10 Spur Accuracy Test

Figure

100

(f)

cdBc/Hz:

Typical Spur Accuracy Test Results

vs f mz:

10K

100K

Page 17

Model 3048A Calibration

Noise Flatness Test

DESCRIPTION

This test verifies that the calibration data used for phase noise measurements above 500 kHz offsets is accurate. It also provides an opportunity to update the calibration data should the flatness be marginal.

The test requires an RF spectrum analyzer in the System's Configuration Table and needs to be run only when an RF analyzer is used while making measurements. (An HP 3585A Spectrum Analyzer is supplied with Systems having Option 101.) The test is a standard phase-lock-loop measurement of the phase noise of the internal 400 MHz and 350-500 MHz Oscillators. The frequency offset range of the measurement is 500 kHz to 40 MHz. The 400 MHz Oscillator has a flat or white phase noise distribution from 500 kHz to 40 MHz.

This test measures the maximum unflatness above 500 kHz relative to the measured noise value at a 500 kHz offset. If the unflatness is equal to or greater than 2 dB, the "CALDATAHI" data file will have supplementary data appended to it to adjust for the unflatness.

EQUIPMENT

Printer. The test requires the presence of a printer in the System's Configuration Table.

PROCEDURE

Press the Spcl. Funct'n softkey available at the Main Software Level menu.

Press the |3048A Sys Chk| softkey.

Press the

6. Connect the instruments as shown on the on-screen connection diagram and in Figure 5

Press the

NOTE

// troubleshoot mode has been selected (by pressing the hey)you will be prompted for the setup diagram two times. Press the

softkey after the second setup diagram is displayed.

Pert. Tests

Noise Flat.

New Msrmnt

Proceed

(but see the following note) and the measured noise should be similar to that shown in Figure 6. (The measurement takes about 5 minutes depending on the controller.)

softkey. softkey. The System will then load the Noise Flatness Test File.

softkey.

softkey. The measurement should proceed automatically without error messages

Test Mode

Proceed

soft-

Noise Flatness Test 11

Page 18

Calibration Model 3048A

NOTE

permissible

degradation

After this test

greater,

supplementary data correct

If you

the

do not

the calibration data from CALDATAHI since

computer

RAM measurements. Also, if changed, System

the

specifications.

2 dB unflatness),

proceed with

message

completes

Store Data

calibration

wish

is displayed

its

measurement,

softkey

mass media storage

data for the paths used by the RF spectrum analyzer.

store

the

(random access memory)

old

data is used while the new data has significantly

accuracy

measurements

the unflatness

the

Store Data softkey will not be

the

test

if an

the degradation

the

will be

displayed.

(in

supplementary data,

and

above

within specifications (less than

accuracy specification

is 1 dB

measured unflatness

This

allows

or less.

you to store the

the file "CALDATAHI")

you

should reload

the new

will

500

data remains

used

kHz

subsequent

may

not

meet

displayed.

HP 3561A DYNAMIC

SIGNAL ANALYZER

2 dB

the

RF SPECTRUM ANALYZER

ac^n DDDD DnDDDDOD DCDDDaDDD

a a

DCDa DDDD

°oo

oooo

Figure

350-500

Noise Flatness Test Setup

MHi 400

MHz

HP 11848A PHASE NOISE INTERFACE

INPUT

3561A

12 Noise Flatness Test

Page 19

Model 3048A

Dec

HP11848A

1987, 15:45:23

S/N

2621A00106

HP11848A NOISE FLATNESS PERFORMANCE TEST

OFFSET

MAX

UNFLATNESS

FREQ RELATIVE

(Hz.) (+/-

6.2E+6

Chp] 304BH Carrier: 400.E+G

120

HP3048H NOISE FLRTNESS PERFORMRNCE TEST

0.83

500 KHz.

dB.)

Hz 30 Dec 1987

iii

15:41:54 - 15:43:59

130

500K

J.I

.,...1

10M

... „ L^„L ,

III

C-F 5 CdBc/Hz]

fCHzD

40M

Figure 6. Typical Noise Flatness Test Results

Noise Flatness Test 13

Page 20

Calibration Model 3048A

Noise Floor Test

DESCRIPTION

This test measures the noise of the System apart from the phase noise contribution of the external reference sources. Thus this test measures the absolute sensitivity (the noise floor) of the System.

The output of the internal 350-500 MHz Oscillator is split and applied to both inputs of the 5 MHz to

1.6 GHz Phase Detector. However, one path to the phase detector is delayed one-quarter wavelength to establish phase quadrature of the split signals. Fine adjustment of quadrature is made by tuning the oscillator until the dc output of the detector is 0V. The phase noise of the oscillator cancels itself out because the phase fluctuations of the split signals are correlated.

EQUIPMENT

Printer. The test requires the presence of a printer inthe System's Configuration Table. Noise Floor Test Fixture. A power splitter with delay line is required for this test. This device is

supplied with the System (HP 11848-61032).

PROCEDURE

Press the Spcl. Funct'n softkey available at the Main Software Level menu.

NOTE

// troubleshoot mode has been selected (by pressing the you will be prompted for the setup diagram two times. Press the

softkey after the second setup diagram is displayed.

Press the |3048A Sys Chk| softkey.

Press the

6. Connect the instruments as shown on the on-screen connection diagram and also Figure 7.

Perf. Tests Noise Floor New Msrmnt

The Interface's SPECTRUM ANALYZER output should either be terminated in 50Q or an RF spectrum analyzer should be connected to it.

Connect the Noise Floor Test Fixture directly to the L and R ports of the PHASE DETECTOR INPUTS. Line length is critical; do not connect

intervening cables.

Tighten all connections securely as the Noise Floor test results may be affected by loose connections. Also, do not mechanically disturb the System while the test is running.

softkey.

softkey. The System will then load the Noise Floor Test File.

softkey.

NOTE

Test Mode

softkey),

Proceed

Press the

and the measured noise should be similar to that shown in Figure 8. (The measurement takes about 30 minutes depending on the controller and the presence of the RF spectrum analyzer.)

14 Noise Floor Test

Proceed

softkey. The measurement should proceed automatically without error messages

Page 21

Model 3048A

NOTE

// no RF spectrum analyzer is present, the test covers offsets of 0.01 Hz to 100 kHz. If an RF analyzer is present the range is 0.01 Hz to 40 MHz.

The phase detector constant is not measured for this test. A phase detector

constant of 0.6

V/radian

is used for the Noise Floor Test because at

the specified R-port power level, the phase detector constant is typically

0.6

V/radian.

HP 3561A DYNAMIC

SIGNAL ANALYZER

Calibration

NOISE FLOOR

TEST FIXTURE

MNOHP

(REAR

iseu

PANEL)

FRO

SOURCE OUTPUT

SPECTRUM

HP 11848A PHASE NOISE INTERFACE

Figure 7. Noise Floor Test Setup

[hp] 304BA Carrier: 400.E+6 Hz 31 Dec 1987 10:43:47 - 11:09:25

-30

- T 1—n

-40

-50

-G0

-70

-B0

- >^

-90

-100

-110

^-=;

-130

-~N~

-130

-140

-150

-1G0

-170

-180

-190

■

iii

HP304GR NOISE FLOOR PERFORMANCE TEST

■

III

■ III -'I™ 1 I ! 1 T TT

\x ""N

^H*

'^^

I III

III

^wyLi

III

SPURIOUS SPEC -

NOISE FLOOR SPEC -

■

III

ANALYZER

1 III

.01

JC C -F

3 CdBc^HzD vs fCHzD

Figure 8. Typical Noise Floor Test Results

100K

Noise Floor Test 15

Page 22

Calibration Model 3048A

Microwave Phase Detector Conversion Loss (Opt. 201) Test

DESCRIPTION

Two microwave sources are set 50 kHz apart. One is connected to the R port of the Interface's 1.2 GHz to 18 GHz (microwave) phase detector; the other is connected to the L port. The phase detector generates a 50 kHz IF beatnote at its output which is measured by the HP 3561 A. The conversion loss of the phase detector is the ratio of the level of the beatnote to the level of the signal at the R port. This procedure is repeated for several carrier frequencies. Because of the high frequencies involved, the

power of the two sources is measured by a power meter for each frequency.

The signal path within the Interface is controlled manually using the 11848A Control feature. The microwave sources are operated manually.

Conversion loss is not an explicitly specified parameter but must be within the limits given in this

procedure to assure specified sensitivity (that is, noise floor) for the stated carrier frequency. Excessive

conversion loss is usually caused or relays.

EQUIPMENT

Microwave Sources. Two microwave sources are required. If the full range of the microwave phase

detector is to be tested, both sources must cover 1.2 to 18 GHz. The drift and short-term instability of both sources must be small compared to 100 kHz. One source must output at least +7 dBm, the other at least 0 dBm. If the required stability is unobtainable, the test can be run with an RF spectrum analyzer (such as the HP 3585A) used in place of the HP 3561A; the source instability must be small compared to 1 MHz. If any other RF spectrum analyzer is used, the output power of the generators should be measured with the power meter.

a defective phase detector (mixer) itself or by interconnecting cables

Power Meter and Sensor. A power meter with sensor is required for this test to check the power into

the L and R ports of the microwave phase detector. The power meter must be able to measure up to

+10 dBm from 1.2 to 18 GHz. Spectrum Analyzer. The HP 3561A Dynamic Signal Analyzer or the HP 3585A Spectrum Analyzer

is recommended but other RF spectrum analyzers can be used. If any other spectrum analyzer is used, the output power of the generators should be made with a power meter.

PROCEDURE

Two signal sources and the spectrum analyzer are connected to the Interface as follows. (Refer to

CAUTION

The

microwave

phase

detector.

the power levels with a power meter before connecting the sources to the

phase

detector.

changing

Figure 9.)

a. Set one microwave source to 1.2 GHz. Measure the power with a power meter and set the

level to 0 dBm. Connect it to the front-panel R input of the 1.2 GHz TO 18 GHz phase detector.

Set the other microwave source 50 kHz above or below 1.2 GHz. Measure the power with a

power meter and set the level to +7 dBm. Connect it to the front-panel L input of the phase detector. (If an RF spectrum analyzer is to be used, a 1 MHz beatnote is suggested.)

phase detector is more

Levels greater than +10 dBm may cause Also, disconnect the

frequency.

susceptible

sources

to burnout than the RF

damage.

from the phase detector

Measure

before

16 Microwave Phase Detector Conversion Loss (Opt. 201) Test

Page 23

Model 3048A Calibration

Preset the HP 3561A for a 0 to 100 kHz frequency span. Connect the HP 3561A's input to the Interface's front-panel TO HP 3561A INPUT output. (If an RF spectrum analyzer is used, set it to view a 1 MHz signal.)

HP 3561A DYNAMIC

SIGNAL ANALYZER

TO HP 3561A INPUT

(CONNECT RF

SPECTRUM ANALYZER OR 50-OHM LOAD HERE.)

SPECTRUM ANALYZER

HP 11848A PHASE NOISE INTERFACE

Figure 9. Microwave Phase Detector Conversion Loss Test Setup

Press the Spci. Funct'n softkey available at the Main Software Level menu.

Press the

Set up the HP 11848A internal configuration as follows.

11848A

a. Press the

Control softkey.

Preset

softkey.

Use the cursor control keys to move the cursor to the "SELECTED 'K' SWITCHES:" line then

key in 12 and 13.

c. Use the cursor control keys to move the cursor to the

SWITCH

NUMBER:"

line then key in 6.

d. Press the |Send Command softkey. This routes the microwave phase detector output to the

front-panel spectrum analyzer output port. The display should appear as in Figure 10. (With 6 showing on the H switch line and 12 and 13 showing on the K switches line, the position of

the switch levers of K12 and K13 is in the state opposite that shown on the Block Diagram

foldout at the end of this manual.)

Set one of the microwave sources to the frequencies indicated in Table 3 below. Set the other source 50 kHz above or below the frequency of the first source. (If an RF spectrum analyzer is being used, set the other source 1 MHz above or below the first source.) For each pair of frequencies, remeasure the power of both sources, reconnect the sources to the phase detector, and read the level of the 50 kHz (or 1 MHz) signal from the spectrum analyzer. The level should be -25 dBV (-12 dBm) or higher.

rev.20APR88

Microwave Phase Detector Conversion Loss (Opt. 201) Test 17

Page 24

Calibration

Model 3048A

DAC1: DAC2: DAC3:

Microwave Source

Frequency

(GHz)

1.2

0 0 0

Table 3.

8 12 18

Conversion

Limits of Beatnote Signal (dBV)

HP 11848A CONTROL

V V V

GAIN1: GAIN2: GAIN3:

Loss Test Results

Lower

-25

Refer

dB dB

Actual

Block Diagram

ATTEN1: ATTEN2: ATTEN3:

xl xl xl

H SWITCH NUMBER:> F SWITCH NUMBER: LAG-LEAD FILTER:

SELECTED SELECTED

'K' 'L'

SELECTED 'S' SWITCHES

Acceptable Values: 0 TO 7

Figure 10. HP

11848A Control Display

6 < 0 0

SWITCHES

12 13

for

Microwave

Phase Detector

Conversion

Loss Test

18 Microwave Phase Detector Conversion Loss (Opt. 201) Test

rev.02FEB88

Page 25

Model 3048A Calibration

Functional Tests

DESCRIPTION

The Functional Tests exercise the hardware in the Interface and check for proper functioning. Examples of the hardware checked are switches, amplifiers, attenuators, DACs, filters, etc. The program permits a run-through of all checks or in some cases a single function can be individually tested.

In a typical test such as the testing of a filter, the program routes the noise source of the HP 3561A

Dynamic Signal Analyzer through a reference path to the input of the HP 3561A and measures the

signal level at several frequencies. The program then inserts the filter in the path and remeasures the levels.

Except for checks of dc offset and VCO control path, test limits are loose because only the general

functioning of the filter is checked. (Measurement path filters are tightly characterized by the Option 1 or Option 2 Calibration program.)

These tests are similar to the tests on the Diagnostic disc. The diagnostic program also includes failure analysis information and thus may be more useful in tracking down a fault than the Functional Tests.

(Refer to the HP 11848A Service Manual.)

EQUIPMENT

Printer. These tests will run without the presence of a printer in the System's Configuration Table. However, the test results in some instances will not remain on the display long enough to be observed; therefore, it is recommended that the tests be run with a printer.

PROCEDURE

Press the

Press the |3048A Sys Chk| softkey.

Press the

To perform all tests sequentially, press the Test All.

Spcl. Funct'n softkey available at the Main Software Level menu.

Fnctl.

Chk.

softkey.

NOTE

The tests may be run as an entire sequence or tests may be run individually as outlined in the following steps. Before proceeding with the tests, you should read the Comments section below.

softkey and follow the displayed instructions.

To perform a specific test, perform the following steps.

Press the

Move the cursor to the desired test.

With the cursor at Test 01, Test 02, or Test 03, press the Select Path softkey then move the cursor to the desired path of the selected test. Press the Sngl Path softkey to test a single path of the selected test or press the

for a description of the test paths.)

Select Test

softkey.

Test all

softkey to test all paths. (Refer to Comments

d. If Test 04 through Test 10 is selected, press the Run Test softkey.

Functional Tests

Page 26

Calibration

Comments

Model 3048A

Runtime. With the printer on the full functional test takes about 25 minutes to run. Some manual reconnection of cables is required.

Connections. Signal connect diagrams or instructions appear on the display as the test or tests proceed. However, two connections are assumed that are not shown. (1) The rear-panel SOURCE OUT connector of the HP 3561A must be connected to the rear-panel NOISE INPUT FROM HP 3561A SOURCE OUTPUT connector of the Interface. (2) The Interface's SPECTRUM ANALYZER output should either be terminated in 50f2 or an RF spectrum analyzer should be connected to it. In either case the spectrum analyzer port must be terminated in 50fi.

Printer

inhibited by pressing the | Printer Off softkey. To re-enable the printer, press the | Printer recommended that tests be run with the printer, otherwise the test results in some instances will not remain on the display long enough to be observed.

If it is desired to have the Interface's serial number appear on the printout, the serial number must appear in the appropriate column of the System's Configuration Table. This practice is recommended.

Tests.

at the end of this manual will help in understanding the descriptions.

On/Off.

A brief description of the ten Functional Tests follows. Referring to the Block Diagram foldout

Test

01.

Test 02. A3/A4 Signal Paths Transfer Functions Test. A3 is the Analyzer Interface Assembly;

Test

03.

If a printer is on HP-IB and in the System's Configuration Table, the printout can be

On|

softkey. It is

DC Offsets Test. The HP 3561A is used as a dc voltmeter to measure the dc level at the

front-panel TO HP 3561A INPUT connector. The voltage is measured with many different circuits in the measurement path. The circuits are labeled for each result. If the voltage is slightly out of limits, in most cases they can be adjusted. (Refer to the Adjustments further on in this manual.)

A4 is the Phase Detector Assembly. The circuit paths checked are between the rear-panel

NOISE INPUT FROM HP 3561A SOURCE OUTPUT connector (J14) to the front-panel TO

HP 3561A INPUT connector (Jll). The print out path descriptions give some idea of the signal flow. A measurement of the simplest path is made first; this becomes a reference for the tests. Measurements are made at several frequencies.

Phase-Lock Loop Paths Transfer Functions Test. This check is similar to Test 02

except that the paths are through the circuits labeled GAIN 1, GAIN 2, and ATTEN 2 on the Block Diagram.

Test 04. Lag-Lead Transfer Functions Test. Lag-Lead Network 1 is measured at 8 different

settings.

Test 05. 100 kHz Calibrator, Search Oscillator, and Out-of-Lock Flip-Flop Test. The

absolute level and frequency of the 100 kHz Calibration Oscillator and the Search Oscillator

are measured. The Out-of-Lock and Overload Flip-Flops are tested when set and cleared.

Test 06. RF Phase Detector Beatnote Test. The (A6) 10 MHz VCXO A and (A7) 10 MHz VCXO

B are fed into the RF Phase Detector. A beatnote of 500 Hz is generated and the amplitude

measured. This test checks the functioning of both oscillators and the RF Phase Detector.

Test 07. DAC 1, 2, and 3 Beatnote Pull Test. This is similar to Test 06, but the oscillators are

individually tuned by each of the three DACs to test their tuning sensitivity.

Test 08. Peak Detector and Switched High-Pass Filter Test. An 800 Hz beatnote is generated

by the method described in Test 06. The beatnote is fed into the Peak Detector following

the 10 Hz/50 kHz High-Pass Filter. The dc output from the Peak Detector is measured with

the 10 Hz then the 50 kHz filter switched in.

Test 09. Rear-Panel Tune Voltage Output Test. The transfer function of ATTEN 1 is measured

by a method similar to Test 02.

Test 10. Front-Panel Tune Voltage Output Test. The transfer function of ATTEN 3 is measured

by a method similar to Test 02.

20 Functional Tests

Page 27

Model 3048A Calibration

DAC Tests

DESCRIPTION

The output of the three Digital-to-Analog Converters (DACs) is measured with each input bit

individually set high. DAC 1 can be tested via a front-panel output. DACs 2 and 3 can only be tested at internal test points. This requires removal of the top cover of the HP 11848A Phase Noise Interface. The HP 3561A Dynamic Signal Analyzer is used as a dc voltmeter in this test.

Since this test requires accessing the interior of the Interface, precautions should be taken to prevent electrical shock. Care should also be taken to minimize electro-static discharge that could damage sensitive electrical devices.

EQUIPMENT

PROCEDURE

The testing of DACs 2 and 3 requires removal of the top cover of the Interface. To do this:

a. Switch LINE to OFF.

Remove the line cord.

c. If the rear panel of the Interface has two feet in the upper corners, remove them.

d. Unscrew the screw in the middle of the rear edge of the top cover. This is a captive screw

and will cause the top cover to push away from the frame. (A slight tapping on the top cover will aid in removal.) Slide the cover back about 6.5 mm (0.25 inch) and lift it off.

e. Reinsert the line cord and switch LINE back to ON.

Press the Spcl. Funct'n softkey available at the Main Software Level menu.

Press the 3048A Sys Chk softkey.

NOTE

Before proceeding with the tests, you should read the Comments section

below.

Press the Dae Tests softkey and follow the displayed instructions.

Comments

Printer

On/Off.

be inhibited by pressing the Printer Off softkey. To re-enable the printer, press the Printer On softkey.

This softkey function is not present at all times during the execution of the tests. It is recommended that tests be run with the printer, otherwise the test results in some instances will not remain on the display long enough to be observed.

If a printer is on HP-IB and in the System's Configuration Table, the printout can

Connections. To test DACs 2 and 3, you will be prompted to connect the HP 3561A input to testpoints on the A3 Analyzer Interface Assembly. A3 is the large printed circuit board under the top cover. (Refer to the HP 11848A Service Manual for details.) The testpoint locations are shown in Figure 11.

DAC Tests 21

Page 28

Calibration

Model 3048A

The specific connections are:

DAC 2: Connect the positive (+) lead (the inner conductor) to A3 TP202. Connect the negative (-) '

lead (the outer conductor) to A3 TP207 (ground). v

DAC 3: Connect the positive (+) lead (the inner conductor) to A3

lead (the outer conductor) to A3 TP207 (ground).

TP201.

Connect the negative (-)

FRONT

TP202

TP201

TP207-

TP203

Analyzer Interface

Assembly

Figure 11. A3 Testpoint Locations

22 DAC Tests

Page 29

Model 3048A

DESCRIPTION

The A3 Analyzer Interface Assembly in the HP 11848A has ten adjustments. The adjustments are guided by the system software but the software neither displays the actual measurement values nor indicates whether the adjustment is within the proper limits; rather, the operator simply reads the value from the HP 3561A and adjusts the specified component until the reading is within limits.

The following adjustments are made:

Calibration

A3 Adjustments

Since these procedures require accessing the interior of the Interface, precautions should be taken to prevent electrical shock. Care should also be taken to minimize electrostatic discharge that could damage sensitive electrical devices.

PROCEDURE

Initial Setup

The adjustments to the A3 Analyzer Interface Assembly require removal of the top cover of the

Set the HP 3561A input switch to the FLOAT position.

Component

A3R68 A3R74 A3R80 A3R86 A3R92 A3R98

A3R132 A3R134

A3R210 A3R206

AC/DC Adaptive Coupler 1 Hz High-Pass Filter 10 Hz High-Pass Filter 100 Hz High-Pass Filter 1 kHz High-Pass Filter 10 kHz High-Pass Filter

Floating Amplifier 2 Floating Amplifier 1

DAC2 DAC3

Circuit

Purpose

Minimize dc offset Minimize dc offset

Minimize dc offset Minimize dc offset Minimize dc offset Minimize dc offset

Maximize ground isolation

Set reference level Set reference level

Interface. To do this:

a. Switch LINE to OFF.

Remove the line cord.

c. If the rear panel of the Interface has two feet in the upper corners, remove them.

d. Unscrew the screw in the middle of the rear edge of the top cover. This is a captive screw

and will cause the top cover to push away from the frame. Slide the cover back about 6.5 mm (0.25 inch) and lift it off.

e. Reinsert the power cord and switch LINE back to ON.

Press the Spcl. Funcf n softkey available at the Main Software Level menu.

Press the 3048A Sys Chk softkey.

Press the Int. Adj'mnt softkey.

6. Press the Adjust

softkey.

A3 Adjustments 23

Page 30

Calibration Model 3048A

NOTE

The physical location of testpoints and adjustable components is shown in Figure 16.

DC Offset Adjustments

The prompt

CONNECT HP11848A

'PHASE DETECTOR OUTPUTS

HP3561A INPUT

HP3561A INPUT'

instructs you to connect the instruments as shown in Figure 12. After making the connections, press the

Proceed

softkey.

8. Make the adjustments for A3R68, A3R74, A3R80, A3R86, A3R92, and A3R98 as instructed.

NOTE

The adjustment limit prompt "0 VDC +/- 300

value

should be between -300 and +300

The

values

"Yr:"

you are monitoring and adjusting appear as the

at the bottom center of the HP

HP 3561A DYNAMIC SIGNAL ANALYZER

(-1

. E

. [o]

HP 1184dA PHASE NOISE INTERFACE

microvolts

3561A

o o

O 0

uV"

means that the adjusted

dc.

value

display.

TO HP 3561A

o o

0 0

INPUT

for "Y:"

24 A3 Adjustments

Figure 12. First A3 Adjustment Setup

Page 31

3048A Calibration

Ground Isolation Adjustments

9. The prompt

CONNECT HP3561A NOISE SOURCE (REAR PANEL) HP3561A

INPUT.

instructs you to connect the HP 3561A as shown in Figure 13. This sets up a reference for the following measurements.

10.

The prompt

CONNECT

'PHASE

]

3ETECT0R OUTPUT

BNC

TEE

TO THE

HP11848A

3561A INPUT

AND

CONNECT

CABLE

FROM

BNC

TEE

HP3561A INPUT

followed by

USING

A CONNECT GROUND SIGNAL

BNC TO

HP3561A NOISE SOURCE LEAD LEAD

CLIP LEAD ADAPTER

HP11848A

TO TO

BNC

CHASSIS GROUND

'TEE'

(ISOLATED GROUND)

FOLLOWS:

instructs you to connect the instruments as shown in Figure 14.

NOTE

Connect the ground (outer

conductor) lead

of the

cliplead

adapter to chassis

ground in the HP 11848A. (Testpoint A3 TP46 is a convenient ground

connection point.)

Connect the other lead (the signal lead or inner conductor) of the

cliplead adapter to the outer conductor of the BNC tee. Note that the outer conductor of the tee is not

chassis

HP 3561A DYNAMIC

ground;

SIGNAL ANALYZER

SOURCE

OUT

(REAR PANEL)

it is an

DDDD DDDD DDDD

DDDD

isolated,

floating

ground.

Figure 13. Second A3 Adjustment Setup

A3 Adjustments 25

Page 32

Calibration Model 3048A

HP 3561A DYNAMIC

SIGNAL ANALYZER

3DC QDU □□ :ac ODD no [an

SOURCE

OUT

(REAR PANEL)

[o]

HP 11848A PHASE NOISE INTERFACE

Figure 14. Third A3 Adjustment Setup

11.

Adjust A3R132 as instructed. Refer to Figure 15 which shows a typical result after adjustment.

12.

The next prompts instruct you to simply move the BNC tee (with cables arid adapters attached)

from its present connection to the HP 11848A front-panel connector labeled TUNE VOLTAGE OUTPUT. Then adjust A3R134 in a manner similar to A3R132 above. (It may also be necessary to use a different ground connection.)

DAC Reference Adjustments

13.

Make the connections, measurements, and adjustments of A3R210 and A3R206 as instructed.

NOTE

Note that "+" refers to the

cliplead

adapter's inner conductor and "-" the

outer conductor.

The adjustment limit prompt "-10 VOLTS +/- 50 mV" means that the

adjusted value should be between

—10.05

and

—9.95

volts.

The adjustment limit prompt "-.323 VOLTS +/- 1 mV" means that the

adjusted value should be between

—324

and

—322

millivolts.

26 A3 Adjustments

Page 33

Model 3048A Calibration

A: MATH

-40 B(V)

/DIV

-120

START: X: 2500 Hz

0 Hz

RANGE:

-40 dBV

SQRT (MAG~2 / Ml~2)

BW: 12.5 Hz

Y: -62.71 dB (V)

i irru-^*~ ■»•«— ■

STOP:

5 000 Hz

Figure 15. Typical Ground Isolation Adjustment

A3 Adjustments 27

Page 34

Calibration

Hz HPF 10 Hz HPF 100 Hz HPF

DC OFFSET

ADJ DC

OFFSET

ADJ DC

OFFSET

ADJ

Model 3048A

TP46

PHASE DETECTOR

OUTPUT/GND

ISOLATION

ADAPTIVE COUPLER

DC OFFSET

_^ OFFSET

HPF

OFFSET

ADJ

AC/DC

ADJ

kHz

ADJ

kHz

ADJ

DAC

ADJ

/t\

^\R132

-~^

—■

/ /

I /

R74 / /

/ /

R80 / /

[®r

R68

nz\^-^

^L®J

—

R86 /

R92

fel

1^1

R98

_^-^@\

R210

[®]

R134

[®] _____^

FRONT

TUNE VOLTAGE OUTPUT/

GND

ISOLATION

ADJ

TP201

28 A3 Adjustments

DAC

«/

ADJ

R206

►

V A3

TP207 TP203 Anolyzer Interface

Figure

16. A3

Testpoint and Adjustment Locations

Assembly

Page 35

Model 3048A

DESCRIPTION

The A4 Phase Detector Assembly in the HP 11848A has six adjustments. The adjustments are guided by the system software but the software neither displays the actual measurement values nor indicates whether the adjustment is within the proper limits; rather, the operator simply reads the value from the measuring instrument (usually the HP 3561A) and adjusts the specified component until the reading is within limits.

The following adjustments are made:

Calibration

A4 Adjustments

EQUIPMENT

RF Spectrum Analyzer. The adjustment of A4C32 requires an HP 3585A Spectrum Analyzer. This

adjustment is necessary only if phase noise measurements to 40 MHz offsets are made. Since an RF spectrum analyzer with a tracking generator must be used and since the program software controls only the HP 3585A, no substitution of equipment is possible. (The software will not run the A4C32 adjustment if an HP 3585A is not in the System's Configuration Table.)

Component

A4R67 A4R51 A4R70

A4R38

A4R278

A4C32

(1)

This adjustment can be done only with the HP 3585A Spectrum Analyzer in the System's

Configuration Table.

Low-Noise Amplifier Low-Noise Amplifier Low-Noise Amplifier

PLL 12 dB Amplifier

DAC1

Low-Noise Amplifier

Circuit

Purpose

Minimize dc offset Match input impedance (50fi) Match low/high frequency gains

Zeros panel meter at maximum sensitivity

Set reference level

High-frequency peaking

(1)

PROCEDURE

Initial Setup

The adjustments to the A4 Phase Detector Assembly require that the assembly be pulled out from

the front panel. (It will be helpful to refer to the figure and procedure for accessing the A4 assembly in the HP 11848A Service Manual.) To do this:

a. Switch LINE to OFF.

Remove the line cord.

c. Remove the plastic trim strip from the top of the front frame.

d. Remove the three Torx screws in the top of the front frame.

e. Remove the three Torx screws in the bottom'of the front frame.

A4 Adjustments 29

Page 36

Calibration Model 3048A

f. Carefully pull the front panel out far enough to access the six adjustment holes in the shield

covering the A4 assembly. Note that it is not necessary to remove the shield from the A4 assembly

to make the adjustments.

g. Reinsert the line cord and switch LINE back to ON.

Set the HP 3561A input switch to the FLOAT position.

Press the Spcl. Funct'n softkey available at the Main Software Level menu.

Press the 3048A Sys Chk softkey.

Press the

Int.

Adj'mnt softkey.

6. Press the Adjust

Low-Noise Amplifier Adjustments

The prompt

instructs you to connect the instruments as shown in Figure 17. After making the connections, press the Proceed softkey.

softkey.

NOTE

no RF spectrum analyzer is in the System's Configuration Table, you will be informed at this time. Press the Proceed softkey to continue the A4 adjustments minus the A4C32 adjustment.

The physical location of testpoints and adjustable components is shown in

Figure 24.

CONNECT HP11848A

'PHASE DETECTOR OUTPUTS

HP3561A INPUT

HP 3561A DYNAMIC

SIGNAL ANALYZER

HP3561A INPUT'

30 A4 Adjustments

DDC □□□ CO •

TO HP 3581A

T. [o]

O O

o o

[°] —'

HP 11848A PHASE NOISE INTERFACE

Figure 17. First A4 Adjustment Setup

o o

INPUT

o o

Page 37

Model 3048A Calibration

8. Make the adjustment for A4R67 as instructed.

NOTE

The adjustment limit prompt "0 VDC +/- 20

mV"

means that the adjusted

value should be between -20 and +20 millivolts dc.

The

value

you are monitoring and adjusting appear as the

the bottom center of the HP On

some

A4 adjustments the \

3561A

to skip the current adjustment and

display.

adj. | softkey

on to the next one.

appears.

value

for

"Y:"

This key permits you

9. The prompt

TERMINATE HP3561A INPUT IN

AND

CONNECT HP3561A

HP3561A NOISE

INPUT AT 'BNC

SOURCE TEE'

OHMS

USING

(REAR PANEL)

'BNC

TEE'

instructs you to connect the instruments as shown in Figure 18. This sets up a 50(7 reference for the following measurements.

HP 3561A DYNAMIC

SIGNAL ANALYZER

Figure 18. Second A4 Adjustment Setup

10.

The prompt

REMOVE

CONNECT

50 OHM

CABLE

TERMINATION

AND

FROM BNC

TEE

FROM

BNC TEE

HP11848A NOISE INPUT

instructs you to remove the 50(7 load from the BNC tee and to connect the instruments as shown in Figure 19. This allows the HP 3561A to compare the loading of the noise input port to the loading of a 50fi termination.

A4 Adjustments 31

Page 38

Calibration Model 3048A

HP 3561A DYNAMIC

SIGNAL ANALYZER

essi

DDDD

DQDD DDDD

DDDD

DDC GDG DO on

SOURCE OUT (REAR PANEL)

NOISE INPUT

HP 11B48A PHASE NOISE INTERFACE

LI]

[—|

o o

0 O

Figure 19. Third A4 Adjustment Setup

11.

Adjust A4R51 as instructed. Refer to Figure 20 which shows a typical result after adjustment.

dB(V)

MATH

RANGE:

SQRT (MAG*2 /

-25 dBV

Ml*

0.5 dB

/DIV

START:

32 A4 Adjustments

12.5 Hz

STOP:

5 000 Hz

BW:

Figure 20. Typical Low-Noise Amplifier Impedance Match Adjustment

Page 39

Model 3048A

12.

The prompt

Calibration

'PHASE

DETECTOR OUTPUTS

CONNECT

HP11848A

HP3561A

INPUT'

HP3561A INPUT

instructs you to connect the instruments as shown in Figure 17 (the same as in step 7).

13.

The prompt

CONNECT HP3561A NOISE SOURCE TO HP11848A AT

'NOISE INPUT FROM HP3561A SOURCE OUTPUT' (REAR PANEL)

instructs you to connect the instruments as shown in Figure 21.

HP 3561A DYNAMIC

SIGNAL ANALYZER

SOURCE

OUT

(REAR PANEL)

CONNECT

NOISE INPUT

FROM

3561A

SOURCE OUTPUT

(REAR PANEL)

jPECTRUM ANALYZER OR 50-OHM LOAD HERE.)

SPECTRUM ANALYZER

HP 11848A PHASE NOISE INTERFACE

Figure 21. Fourth A4 Adjustment Setup

14.

Adjust A4R70 as instructed. The result should be similar to the one in Figure 20.

Phase Lock Loop 12 dB Amplifier Adjustment

15.

Adjust A4R38 to zero the panel meter as instructed.

DAC 1 Adjustment

16.

Adjust A4R278 as instructed.

NOTE

The adjustment limit prompt "+10 VOLTS +/- .05 VOLTS" means that the

adjusted value should be between +9.95 and +10.05 volts.

If there is no HP 3585A Spectrum Analyzer on HP-IB, the adjustments

will end after this adjustment.

A4 Adjustments 33

Page 40

Calibration Model 3048A

Low-Noise Amplifier Peaking Adjustment

17.

The prompt

CONNECT HP3585A TRACKING HP11848A REAR PANEL

'INPUT FROM HP3585A

followed by

CONNECT HP3585A 50 OHM INPUT TO HP11848A PHASE DETECTOR OUTPUT AT 'SPECTRUM ANALYZER'

instructs you to connect the instruments as shown in Figure 22. Also, check that the tracking generator level is maximum.

18.

Adjust A4C32 using a non-metallic tuning tool. The adjustment is most easily done by setting the

RF spectrum analyzer to local (press the LOCAL key) then moving the marker with the knob. The adjustment is correct when the level of the highest point on the trace is opposite and equal to the lowest point (usually 40 MHz). A typical adjustment is shown in Figure 23.

GENERATOR

AT:

TRACKING

OUTPUT

GENERATOR'

34 A4 Adjustments

Figure 22. Fifth A4 Adjustment Setup

Page 41

Model 3048A

Calibration

REF -20.0 dBv

1 dB/DIV RANGE -

_ _ _

START .0 Hz

RBW 30 KHz

MARKER

30 dBv

VBW 30 KHz ST .2 SEC

40 000 000.0 Hz

-1.52 dB

STOP 40 000 000.0 Hz

t— -

Figure 23. Typical Low-Noise Amplifier Peaking Adjustment

A4 Adjustments 35

Page 42

Calibration

Model 3048A

DAC 1

VOLT ADJ

R278

R38

LNA

PEAKING ADJ

R67

R70 ^/®

R51

LNA DC

OFFSET ADJ

LNA LF

GAIN ADJ

LNA LF

INPUT 2 ADJ

METER

ZERO ADJ

FRONT

^^F?-

36 A4 Adjustments

Phase Detector

Assembly

Figure 24. A4 Testpoint and Adjustment Locations

Page 43

Model 3048A

DESCRIPTION

The Option 1 Calibration program characterizes the gain and flatness of signal paths internal to the HP 11848A Phase Noise Interface. These unique characteristics are calibration factors which scale the measurement results for best noise measurement accuracy.

For frequencies of 100 kHz and below, the calibration program sets up the HP 3561A as a scalar network analyzer. The internal noise source of the HP 3561A is the input signal to the network under test and the spectrum analyzer function measures the magnitude of the output from the network. For frequencies of 100 kHz through 40 MHz, the HP 3585A (which is required for this frequency range) is used with its internal tracking generator used as the stimulus.

Calibration

Option 1 Calibration

NOTE

Option 1 Calibration is similar to Option 2 Calibration. However, Option 2 Calibration collects data to characterize two additional reference paths.

Perform Option 2 Calibration annually. Perform Option 1 Calibration when

significant ambient changes occur.

The collected data is stored in two files in mass media storage titled "CALDATALO" and "CALDATAHI". Since the data is unique to each individual HP 11848A, it is important that the two files be transferred along with the Interface should the Interface be moved to another System. The data should be tagged to the serial number of the Interface it represents. (The Interface's serial number is logged

in the System's Configuration Table.) Note, however, that the data is not unique to the HP 3561A (or HP 3585A) spectrum analyzer.

EQUIPMENT

Spectrum Analyzer. The System collects data through offsets of 100 kHz with the HP 3561A. Data

through 40 MHz offsets requires, in addition, an HP 3585A Spectrum Analyzer. Since an RF spectrum analyzer with a tracking generator must be used and since the program software controls only the HP 3585A, no substitution of equipment is possible.

PROCEDURE

Initial Setup

Set the HP 3561A input switch to the FLOAT position.

Press the Spcl. Funct'n softkey available at the Main Software Level menu.

Press the 3048A Sys Chk softkey.

NOTE

Before proceeding with the measurements, you should read the Comments

section below.

Press the Cal System softkey.

Option 1 Calibration 37

Page 44

Calibration

Calibration to 100 kHz Offsets

Press the

CaltolOOkHz

softkey.

6. Press the Option 1 softkey.

Connect the cables as prompted on the display and as shown in Figure 25.

HP 3561A DYNAMIC

SIGNAL ANALYZER

SOURCE

OUT

(REAR PANEL)

TO INPUT

(CONNECT

NOISE INPUT

FROM

3561A

SOURCE OUTPUT

(REAR PANEL)

HP 11848A PHASE NOISE INTERFACE

SPECTRUM ANALYZER OR 50-OHM LOAD HERE.)

SPECTRUM ANALVZER

Model 3048A

3561A

Figure 25. First Option 1 Calibration Setup

8. When the prompt appears asking if you want to store the data taken, you have the following choices.

• If you do not want to store the data, press the

Abort

softkey. This will cause the old data from the mass storage media to be re-loaded in computer RAM (random access memory) and thus destroy the data just collected.

If you want simply to replace the old data with the new data on the current mass media storage device, press the | Store Caldata softkey and overwrite the data in the file. (If you abort at this point, the new data still remains in computer RAM.)

• If you want to store the new data on a new disc or mass media file location while keeping the old data, place a new disc in place of the old one then press the

Store Caldata

softkey. (If you abort at

this point, the new data still remains in computer RAM.)

NOTE

Difficulties encountered in storing calibration data in mass storage generate

prompts to assist in clearing the problem. A common example of a problem

is a write-protected floppy disc. This is the end of Option 1 Calibration if no HP 3585A Spectrum Analyzer

is present.

Calibration 100 kHz through 40 MHz Offsets

9. Press the Cal System] softkey.

10.

Press the

11.

Make the cable connections as prompted on the display and as shown in part in Figure 26.

12.

Press the Option 1 softkey and continue with the cable connections as show in Figure 26.

13.

Store the data as outlined in step 8 above.

Cal to 40 MHz

38 Option 1 Calibration

softkey.

Page 45

Model 3048A Calibration

Comments

TRACKING

GENERATOR

Printer

of measurement results can

pressing

On/Off.

the key

a printer

will toggle

is in

the System's Configuration Table, the feature which permits printing

enabled

the

printout feature.

printer.

Plot

On/Off. A feature which permits plotting

Plot

disabled. When When plotting

is displayed

and the

the

enabled,

program pauses insertion loss and frequency cursor control keys

are

for

unsmoothed ("raw") transfer function data. marker softkey), used by the System

HP 3585A SPECTRUM ANALYZER

[a a z

J^U

o o o o

(or

knob).

the

marker

making phase-noise measurements).

|DDD|

□"□ I

[ a p

DCDD DDOD DaDDDDDD

□ czmooQnn

ano DDDO

Plot

Off

measurement

one

If the

and

displayed values

disabled. When

It is

the measured transfer functions

the

Printer

recommended that

Printer Off softkey appears,

the

tests

be run

can be

with

enabled

softkey appears, pressing the key will toggle the plot feature.

of a

path

completed, a plot

permit examination

two markers. The position

Marker 1 softkey

the | Marker

are for

displayed,

smoothed data (which

the plot.

the markers can be moved by

the

softkey

HP 3561A DYNAMIC

SIGNAL ANALYZER

of the

The

marker

displayed (by toggling

HP 11848A PHASE

NOISE INTERFACE

transfer function

display also shows

and

displayed values

actually

INPUT

the

3561A

the

data

Figure

26.

Second Option 1

Calibration

Setup

Option 1 Calibration

Page 46

Calibration Model 3048A

Option 2 Calibration

DESCRIPTION

The Option 2 Calibration program characterizes the gain and flatness of signal paths internal to the HP 11848A Phase Noise Interface. These unique characteristics are calibration factors which scale the measurement results for best noise measurement accuracy.

NOTE

The collected data is stored in two files in mass media storage titled "CALDATALO" and "CALDATAHF. Since the data is unique to each individual HP 11848A, it is important that the two transferred along with the Interface should the Interface be moved to another System. The data should be tagged to the serial number of the Interface it represents. (The Interface's serial number is logged in the System's Configuration Table.) Note, however, that the data is not unique to the HP 3561A (or HP 3585A) spectrum analyzer.

EQUIPMENT

Spectrum Analyzer. The System collects data through offsets of 100 kHz with the HP 3561A. Data

Option 2 Calibration is similar to Option 1

2 Calibration

Perform Option 2

collects

Calibration

data to characterize two additional

annually.

Calibration.

However,

reference

Option

paths.

files

PROCEDURE

Initial Setup

Set the HP 3561A input switch to the FLOAT position.

Press the

Press the |3048A

Press the

40 Option 2 Calibration

Spcl.

Before proceeding with the measurements, you should read the Comments

section

Cai

System softkey.

Funct'n softkey available at the Main Software Level menu.

Sys

Chk|

softkey.

NOTE

below.

Page 47

Model 3048A Calibration

Calibration to 100 kHz Offsets

Press the CaltolOOkHz softkey.

6. Press the Option 2 softkey.

Connect the cables as prompted on the display and as shown in Figure 27.

HP 3561A DYNAMIC

SIGNAL ANALYZER

TO HP 3561A INPUT

(CONNECT RF

NOISE INPUT

FROM HP 3561A

SOURCE OUTPUT

(REAR PANEL)

SPECTRUM ANALYZER OR 50-OHU LOAD HERE.)

SPECTRUM ANALYZER

HP 11848A PHASE NOISE INTERFACE

Figure 27. First Option 2 Calibration Setup

8. The prompt

TERMINATE HP3561A INPUT IN 50 OHMS USING 'BNC TEE'

followed by

CONNECT HP3561A NOISE SOURCE (REAR PANEL) TO HP3561A INPUT AT 'BNC TEE"

instructs you to connect the instruments as shown in Figure 28. This sets up a 50fi reference for the following measurements.

9. The prompt

CONNECT HP3561A NOISE SOURCE (REAR PANEL)

HP11848A NOISE INPUT (FRONT PANEL)

followed

REMOVE 50 OHM TERMINATION AND 'BNC TEE' FROM

HP3561A INPUT.

Option 2 Calibration 41

Page 48

Calibration Model 3048A

HP 3561A DYNAMIC

SIGNAL ANALYZER

Figure 28. Second Option 2 Calibration Setup

followed by

CONNECT HP11848A PHASE DETECTOR OUTPUT LABELED

'TO

HP3561A INPUT'

HP3561A INPUT.

followed

BE SURE THAT HP11848A PHASE DETECTOR OUTPUT LABELED "SPECTRUM ANALYZER'

OHMS.

TERMINATED

instructs you to connect the instruments as shown in Figure 29.

10.

The prompt

RE-CONNECT HP3561A NOISE SOURCE (REAR PANEL) TO HP11848A REAR PANEL AT '3561A NOISE*

instructs you to connect the instruments as shown in Figure 27 (the same as in step 7).

11.

When the prompt appears asking if you want to store the data taken, you have the following choices.

• If you do not want to store the data, press the

Abort

softkey. This will cause the old data from the mass storage media to be re-loaded in computer RAM (random access memory) and thus destroy the data just collected.

• If you want simply to replace the old data with the new data on the current mass media storage device, press the | Store Caldata softkey and overwrite the data in the file. (If you abort at this point, the new data still remains in computer RAM.)

• If you want to store the new data on a new disc or mass media file location while keeping the old data, place a new disc in place of the old one then press the this point, the new data still remains in computer RAM.)

42 Option 2 Calibration

Store Caldata softkey. (If you abort at

Page 49

Model 3048A

HP 3561A DYNAMIC

SIGNAL ANALYZER

DDDD

0 O 0 O

NOISE INPUT

fl:

HP 11848A PHASE NOISE INTERFACE

O O

Figure 29. Third Option 2 Calibration Setup

TO HP INPUT .

(CONNECT RF SPECTRUM ANALYZER

OR 50-OHM LOAD HERE.)

SPECTRUM ANALYZER

Calibration

3561*

NOTE

Difficulties encountered in storing calibration data in mass storage generate

prompts to assist in clearing the problem. A common example of a problem

is a write-protected floppy disc. This is the end of Option 2 Calibration if no HP 3585A Spectrum Analyzer

is present.

Calibration 100 kHz through 40 MHz Offsets

12.

Press the |Cal System| softkey.

13.

Press the

14.

Make the cable connections as prompted on the display and as shown in part in Figure 30.

15.

Press the Option 2 softkey and continue with the cable connections as show in Figure 30. Also, check

Cal to 40 MHz

softkey.

that the tracking generator level is maximum.

16.

The prompt

CONNECT HP3585A TRACKING GENERATOR HP3585A

50 OHM

INPUT

instructs you to connect the HP 3585A as shown in Figure 31.

Option 2 Calibration 43

Page 50

Calibration Model 3048A

HP 3561A DYNAMIC

SIGNAL ANALYZER

HP 3585A SPECTRUM ANALYZER

□ □

TRACKING

GENERATOR

□

:: I

["□"oa

Qczm

DODO DnDDDDDD DQDDDDDD

QCZID DDDD

o o o o

HP 11848A PHASE NOISE INTERFACE

INPUT

3561A

17.

The

prompt

Figure

30.

Fourth Option 2 Calibration Setup

HP 3585A SPECTRUM ANALYZER

aaa

□ an

Figure

aCDD DDDD DCDDDDDDD OnDDDDDD

[a a □

DQD DDDD

31.

Fifth Option 2 Calibration Setup

Dan □ a a

CONNECT HP3585A TRACKING GENERATOR HP11848A 'NOISE INPUT' (FRONT PANEL)

followed

instructs you

44 Option 2 Calibration

CONNECT HP11848A PHASE DETECTOR OUTPUT LABELLED

'SPECTRUM ANALYZER'

connect

the

instruments

shown

HP3585A

Figure

OHM INPUT

32.

Page 51

Model 3048A Calibration

HP 3561A DYNAMIC

SIGNAL ANALYZER

HP 3585A SPECTRUM ANALYZER

[DOC

□ ™r.

[

□ □

DOD DDDD

DaaaaocD

p :: ] [ □ D a

DaDDDDDD

]

DITID DDDD

n n D o □ n

□ D n o o n

NOISE INPUT

FROM HP 3561A

SOURCE OUTPUT

(REAR PANEL)

NOISE INPUT

50-75n

HP 11848A PHASE NOISE INTERFACE

Figure 32. Sixth Option 2 Calibration Setup

18.

The prompt

RE-CONNECT HP3585A TRACKING GENERATOR OUTPUT HP11848A REAR PANEL

AT:

•INPUT FROM HP3585A TRACKING GENERATOR

instructs you to connect the instruments as shown in Figure 30 (the same as in step 15).

19.

Store the data as outlined in step 11 above.

TO HP 3561A INPUT

Comments

Printer

of measurement results can be enabled or disabled. When the pressing the key will toggle the printout feature. It is recommended that the tests be run with a printer.

Plot

disabled. When the Plot

When plotting is enabled, as measurement of a path is completed, a plot of the transfer function

is displayed and the program pauses to permit examination of the plot. The display also shows the insertion loss and frequency of one of two markers. The position of the markers can be moved by the cursor control keys (or knob). If the Marker 1 softkey is displayed, the marker and displayed values

are for unsmoothed ("raw") transfer function data. If the marker softkey), the marker and displayed values are for smoothed data (which is actually the data used by the System in making phase-noise measurements).

On/Off.

If a printer is in the System's Configuration Table, the feature which permits printing

Printer On

Printer Off

softkey appears,

A feature which permits plotting of the measured transfer functions can be enabled or

or Plot Off softkey appears, pressing the key will toggle the plot feature.

Marker 2

softkey is displayed (by toggling the

Option 2 Calibration 45

Page 52

Calibration

DESCRIPTION

The Internal Sources Calibration program determines the settings of DACs 2 and 3 which tune three of the four internal Oscillators to their nominal frequencies. This is a software controlled adjustment. (The three oscillators are 10 MHz A, 10 MHz B, and 350-500 MHz.) The tuning (or frequency set) data is then recorded on the System's mass storage medium as VNOMs in the CALDATAHI file. As with the Option 1 and Option 2 Calibration, this data must be used only with the HP 11848A for which the data was taken.

EQUIPMENT

Frequency Counter. A general purpose 550 MHz counter is required. It does not need to be programmable.

PROCEDURE

Initial Setup

Press the Spcl. Funct'n softkey available at the Main Software Level menu.

Press the 3048A Sys Chk softkey.

Model 3048A

Internal Sources Calibration

Press the |Cal System| softkey.

Press the

Calibration of the 10 MHz A Oscillator

6. Connect the cable from the HP 11848A front-panel 10 MHz A source output to the counter's input as prompted.

8. The prompt

readies you for the HP 11848A CONTROL display. To adjust the DACs:

a. Use the vertical cursor control keys or knob to move the cursor field (" > <") to DAC2.

Note the frequency on the counter. If it is within ±10 Hz of 10 MHz, press the DONE softkey

and continue on to step 10.

c. If the frequency is out of limits, change the voltage of DAC2 by keying in a new voltage within,

the cursor field then press the Send Command softkey. If the voltage does not bring the frequency within limits, key in another voltage. If the voltage settings are too coarse to reach the frequency

limits,

Cal Int Srcs Cal All Srcs

Step 5 sets up the tests for all three oscillators. The other softkeys allow

selection of the individual tests.

cursor down to DAC3 and set it in a similar manner.

softkey. softkey.

NOTE

Press 'Proceed' TO ACCESS HP11848A FRONT PANEL

Then adjust DAC2

MHz +/- 10 Hz.

You may return from 'Front Panel' by pressing 'DONE'

and

DAC3

for a

frequency reading

46 Internal Sources Calibration

Page 53

3048A

NOTE

For all

The

oscillators

MHz A

increasing the voltage decreases the frequency.

Oscillator

has a tuning sensitivity of approximately 20 Hz/V.

DAC2 can be set only in 50 mV increments; DAC3 in 1 mV increments. The acceptable range of

voltages

are listed

below

the last entry of the display.

Calibration

If an unacceptable value is

entered,

the DAC

voltage,

after giving the send

command, will either be unchanged, rounded off, or a prompt will indicate

that the entry needs modification.

Calibration of the 10 MHz B Oscillator

10.

Connect the cable from the HP 11848A front-panel 10 MHz B source output to the counter's input

as prompted.

11.

The prompt

Press 'Proceed' Then adjust DAC2

MHz +/- 50 Hz.

ACCESS HP11848A FRONT PANEL

and

DAC3

for a

frequency reading

You may return from 'Front Panel' by pressing 'DONE'

readies you for the HP 11848A

12.

To adjust the DACs, proceed as in step 9 to bring the frequency within ±50 Hz of 10 MHz, then

CONTROL

display.

press the DONE softkey and continue on to step 13. (The tuning sensitivity is about 200 Hz/V.)

Calibration of the 350-500 MHz Oscillator

13.

Connect the cable from the HP 11848A front-panel 350-500 MHz source output to the counter's

input as prompted.

14.

The prompt

Press 'Proceed' Then adjust DAC2 400

MHz +/- 1 MHz.

ACCESS HP11848A FRONT PANEL

and

DAC3

for a

frequency reading

You may return from 'Front Panel' by pressing 'DONE'

readies you for the

15.

To adjust the DACs, proceed as in step 9 to bring the frequency between 399 and 401 MHz, then

11848A CONTROL display.

press the DONE softkey. (The tuning sensitivity is about 20 MHz/V.)

Storing the Data

16.

As you are prompted for the 10 MHz A oscillator, press either the

you want to store the new VNOM in mass storage or the

softkey to indicate you want to retain

Abort

Proceed

softkey to indicate that

the old VNOM. Actual storing of data is in step 19.

17.

As you are prompted for the 10 MHz B oscillator, press either the

you want to store the new VNOM in mass storage or the

softkey to indicate you want to retain

Abort

Proceed

softkey to indicate that

the old VNOM. Actual storing of data is in step 19.

18.

As you are prompted for the 350-500 MHz oscillator, press either the

that you want to store the new VNOM in mass storage or the

softkey to indicate you want to

Abort

Proceed

softkey to indicate

retain the old VNOM. Actual storing of data is in step 19.

Internal Sources Calibration 47

Page 54

Calibration

19.

20.

Model 3048A

As you are prompted, press either the Store Caldata softkey to permanently store the specified new

VNOMs in mass storage or the |Abort| softkey to leave the current VNOMs unchanged. Stored new VNOMs will overwrite the old VNOMs

If you have requested permanent storage of the new VNOMs, the display will prompt you for

confirmation of this decision. Press the

|Yes,

Proceed

NOTE

softkey to store the new VNOMs.

Difficulties encountered in storing the VNOMs in mass storage generate prompts to assist in

is a

write-protected floppy

clearing

disc.

the

problem.

A common example of a problem

Press the

View Vnoms

softkey to confirm the

values

of the stored VNOMs.

48 Internal Sources Calibration

Page 55

Model 3048A Calibration

Spectral Purity Tests for Options 001 and 002

DESCRIPTION

Option 001 adds an HP 8662A Synthesized Signal Generator as a System reference source. Option 002 adds an HP 8663A Synthesized Signal Generator as a System reference source. To test the spectral purity of these options, an absolute, phase-lock-loop, phase-noise measurement is made with the signal

generator in the System vs. another signal generator of the same type. The test is run only for a carrier

of 1270 MHz.

NOTE

The phase noise measurement result is the combined noise of both signal generators. Both generators together must meet the specified noise level. If one or both generators do not meet the specification, a third generator

must be measured vs. each of the other two generators to determine

which generator is not within specification. This procedure is known as a three-oscillator comparison test.

EQUIPMENT

Printer. These tests will run without the presence of a printer in the System's Configuration Table. It

is recommended that the test be run with a printer.

Reference Signal Generator. The reference generator can be either an HP 8662A Option 003 or an HP 8663A Option 003 Synthesized Signal Generator.

RF Spectrum Analyzer. The System collects data to 100 kHz offsets with the HP 3561A. Data to 40

MHz offsets requires, in addition, an RF spectrum analyzer. Any supported RF spectrum analyzer can be used in this test. However, all specified effects are covered with the HP 3561A. An RF analyzer is needed only if informational data beyond 100 kHz is desired.

PROCEDURE

Press the Define Msrmnt softkey. This softkey appears at the Main Software Level Menu.

Press the Test Files softkey.

Press the Next Page softkey until the file name "HP TEST HP 8662/63 vs HP 8662/63 ABS Q

When the file has been loaded, press the DONE softkey.

1270MHz" appears in the table of file names. Move the cursor until it encompasses the file name

and press the Load File softkey.

NOTE

This file has been set up specifically to measure the HP 8662A and HP 8663A Synthesized Signal Generators and all entries in the Define Measurement Parameter for these sources. It is assumed that the System's HP 8662A or HP 8663A

is in the System's Configuration Table.

Table

have been set for best measurement

accuracy

Press the DONE softkey to select the Main Software Level Menu.

6. Press the

Connect the instruments as shown on the on-screen connection diagram and in Figure 33.

New

Msrmnt softkey.

Spectral Purity Tests for Options 001 and 002 49

Page 56

Calibration Model 3048A

HP 8662A OR 8663A

SYNTHESIZED SIGNAL GENERATOR

HP 3561A DYNAMIC

SIGNAL ANALYZER

RF OUTPUT

NOISE INPUT

FROM

3561A

SOURCE

OUTPUT

(REAR PANEL)

HP 11B48A PHASE

NOISE INTERFACE

»(CONNECT

SPECTRUM ANALYZER

Figure 33. Spectral Purity Tests for Options 001 and 002 Setup

8. Press the Proceed softkey. The measurement should proceed automatically without error messages. The measured spurious signals, as read from the measurement results plot, should be less than

-70 dBc for frequency offsets less than 300 Hz and less than -84 dBc for offsets greater than

300 Hz. The measured noise should be with the limits given in the following table.

Spurious Signal Limit for Offsets <300 Hz:, Spurious Signal Limit for Offsets >300 Hz:

Offset

Frequency

(Hz)

100

1 000

10 000

100 000

Noise Level (dBc)

Actual

Maximum

-48

-78

-97

-112

-124

-126

-70 dBc

-84 dBc

Spectral Purity Tests for Options 001 and 002

Page 57

Model 3048A Calibration

Spectral Purity Tests for Options 003 and 004

DESCRIPTION

Option 003 adds an HP 11729C Carrier Noise Test Set as a down-converter to the System reference source. Option 004 adds an HP 11729C Option 130 Carrier Noise Test Set (with an AM detector) as a down-converter to the System reference source. The reference source can be either an HP 8662A Option 003 or an HP 8663A Option 003.

This test measures the absolute noise floor of the System including the contributions of two reference sources and two down-converters. (Refer to the functional diagram of Figure 34.) The test method measures the sum of the noise of two down-converters (including the noise of their respective 640 MHz reference sources—Source 2 and Source 3) by having each one down-convert a common source

(Source 1). The noise of the common source is then cancelled in the phase detector. Quadrature is

maintained by phase locking.

Tuning is via the electronic frequency control (EFC) port of one of the 640 MHz sources. Source 1 is an independent microwave signal generator or simply the main RF output of one of the HP 8662As or HP 8663As (which, by multiplying up its time base reference, supplies the 640 MHz Source 2 or

Source 3).

SOURCE 1

NOTE

Since the noise floor measurement result includes the combined noise of both down-converters and signal

together must be better than the specified noise not meet

8663As should be

specification,

tested.

SOURCE 2 V\s,

the

The procedure to do this is found in Appendix B.

1*640

MHz

640

generators,

MHz

references

all sources (except Source 1)

level.

If the test results do

from the HP

8662As

or HP

Figure 34. Functional Diagram of the Spectral Purity Tests

Spectral Purity Tests for Options 003 and 004 51

Page 58

Calibration Model 3048A

EQUIPMENT

Carrier Noise Test Set. A second HP 11729C is required in addition to the one in the System.

Reference Signal Generator. A second HP 8662A Option 003 or HP 8663A Option 003 Synthesized

Signal Generator is required in addition to the one in the System. Frequency Doubler. If two HP 8662As are used, a frequency doubler is required. The recommended

model is HP 11721A. Power Splitter. The generally recommended model is HP 11667A; it has a very wide frequency range

but 6 dB loss. Other splitters such as Minicircuits ZAPD-4 have typically 3 dB loss but the frequency range is restricted.

Printer. These tests will run without the presence of a printer in the System's Configuration Table.

However, it is recommended that the test be run with a printer.

RF Spectrum Analyzer. The System collects data to 100 kHz offsets with the HP 3561A. Data to 40 MHz offsets requires, in addition, an RF spectrum analyzer. Any supported RF spectrum analyzer can be used in this test. However, all specified effects are covered with the HP 3561A. An RF analyzer is needed only if informational data beyond 100 kHz is desired.

PROCEDURE

The HP 3048A Noise Floor Test should be run before running this test.

Press the Define Msrmnt softkey. This softkey appears at the Main Software Level menu.

Press the Test Files softkey.

Press the

8662/63" and press the Load File softkey.

When the file has been loaded, press the DONE softkey.

6. Press the DONE softkey again to select the Main Software Level menu.

Press the

8. Connect the instruments as shown in Figure 35 and set the non-controlled instruments as instructed in the following steps a and read the following notes.

Page softkey until the file name "HP TEST HP 11729C/8662/63 vs HP 11729C/

appears in the table of file names. Move the cursor until it encompasses the file name

NOTE

This file has been set up specifically to measure the HP 8662A and

8663A Test set for best measurement

11729C (which

New

Synthesized Signal

Sets.

All entries in the

actually needs to be entered in System's Configuration Table

allows

Msrmnt softkey.

the System to select its center band).

Generators

Define

accuracy

However, before connecting and setting the instruments,

and the HP

Measurement

for these

sources.

11729C

Parameter Table have

However,

Carrier Noise

only the first

been

a. Normally, you will set the level of the second source (driving the power splitter) to +13 dBm,

and set its frequency to 2116.7 MHz (into the splitter). (But see the following notes.)

Set the second HP 11729C FILTER RANGE CENTER BAND to 1.92 GHz. (Or, in general,

set the center band to frequency that matches the RF or microwave input frequency.)

52 Spectral Purity Tests for Options 003 and 004

Page 59

Model 3048A Calibration

HP 3561A DYNAMIC

SIGNAL ANALYZER

HP 1184BA

PHASE NOISE

INTERFACE

W1 LENGTH W3 LENGTH

Figure 35. Spectral Purity Tests for Options 003 and 004 Setup

HP TEST 11729C/B662/63 VS. 11729C/8S62/63

LhpD 3048R Carrier: 2.1167E+9 Hz 19 Jan 1988 15:14

-10

-20

-30

-40

-50

-60

-70

Nw,

- X.

-80

-90

- ^s

-100

-110

-120

-130

-140

-150

-160

-170

■ 111

10 100 IK 10K 100K 1M

Nyl

.ilUu

■hlLi'lIMim

i iii

i 1,

lli On

~--"n*

i III

£Cf) CdBc/Hz] vs fCHz3

VJU-U

■ III

■•si

■ III ■ III

_».

MICROWAVE

SIGNAL SOURCE

HBS NSE

32 - 15:19:54

i III

■

10M

40M

Figure 36. Typical Spectral Purity Tests Results

Spectral Purity Tests for Options 003 and 004 53

Page 60

Calibration

NOTE

The on-screen connection

diagram,

while showing the general measurement technique, is incomplete. Also note that neither of the HP 8662As or HP 8663As nor the second HP

11729C

in Figure 35 are under HP-IB

control.

Either the first

source,

the

second

source,

an independent third

source

can be used to drive the power splitter.

The recommended input drive level to each of the two HP +7 dBm; although, for the 1.28 and 3.20 GHz frequency adequate. Thus, if an HP is

used,

the source driving the power splitter optimally should be set to

2116.7

MHz at +13 dBm, but a level as

11667A Power

Splitter (with a nominal 6 dB loss)

low

as +6 dBm is adequate.

band,

11729Cs

0 dBm is

Model 3048A

4. If the source driving the power splitter (such as the HP a doubler, set the source's frequency to high

as possible

(+16 to +20 dBm) to generate at least 0 dBm at the output

1058.35

MHz and set its level as

8662A)

requires

of the doubler.

5. The frequency of

2116.7

MHz was chosen to minimize the number of

significant spurious signals.

6. Other sources can be used to perform this test at higher frequencies.

It is important to

the center bands of the HP

spectral purity

observe

the power requirements stated

11729Cs

specifications

at other

to match the

frequencies,

carrier

above

frequency.

and to set

For the

refer to the Specifications

section of the Reference Manual.

Press the Proceed softkey. The measurement should proceed automatically. The measured noise should be similar to that shown in Figure 36 and should be within the limits given in the following table.

NOTE

// the beatndte frequency is too high, the System cannot tune the (EFC) source close enough to

acquire

phase

lock.

Various error messages on the display warn of this condition. You must then manually adjust either 640 MHz source (in the HP frequency of the and*HP

8663A,

sources

the adjustment is located on the

8662As

within the

or HP

loop's

8663As)

capture

to bring the difference

range.

rear

(For

the HP

panel and is

labeled

8662A

?FINE FREQUENCY ADJUST".;

this test fails, perform the HP 8662A or HP 8663A 640 MHz Spectral

• Purity Test in Appendix B.

Offset

Frequency

(Hz)

100

1 000

10 000

100 000

••v^/'

54 Spectral Purity Tests for Options 003 and 004

Noise Level (dBc)

Actual

Maximum

-44

-74

-94

-110

-130

-140

Page 61

Model 3048A Calibration

Spectral Purity Tests for Options 005 and 006

DESCRIPTION

Option 005 adds an HP 8642A Signal Generator Option 001 as a System reference source. Option 006 adds an HP 8642B Signal Generator Option 001 as a System reference source. (Option 001 in the HP 8642A or HP 8642B adds a high-stability timebase reference.) To test the spectral purity of these options, an absolute, phase-lock-loop, phase-noise measurement is made with the signal generator in the System vs. another signal generator of the same performance or better. The test is run only for a carrier of 640 MHz.

NOTE

The phase noise measurement result is the combined noise of both signal generators. If a second HP 8642A or HP 8642B Signal Generator is specified noise level should be raised 3 dB. Then, if one or both generators do not meet the specification, a third generator must be measured vs. each of the other two generators to determine which generator is not within specification. This procedure is known as a three-oscillator comparison test.

used,

the

EQUIPMENT

Printer. These tests will run without the presence of a printer in the System's Configuration Table. It

is recommended that the test be run with a printer.

Reference Signal Generator. The reference signal generator must have phase noise performance that

equals or exceeds the specifications for the HP 8642A or HP 8642B under test. Possible reference

sources include the 640 MHz reference from an HP 8662A Option 003 or HP 8663A Option 003

Synthesized Signal Generator or a second HP 8642A or HP 8642B Signal Generator (which need not have Option 001). None of the sources need to be in the System's Configuration Table, but one may be.

Having the System's HP 8642A or HP 8642B in the table will put it under automatic control.

RF Spectrum Analyzer. The System collects data to 100 kHz offsets with the HP 3561A. Although the System has a specification at 200 kHz offsets, data taken at 100 kHz offsets is adequate and thus eliminates the need for an RF spectrum analyzer. However, any supported RF spectrum analyzer, such as the HP 3585A Spectrum Analyzer, can be used in this test. With an RF spectrum analyzer connected, data to 40 MHz offsets will be displayed.

PROCEDURE

Press the Define Msrmnt softkey. This softkey appears at the Main Software Level menu

Press the Test Files softkey.

Press the Next Page softkey until the file name "HP TEST HP 8642A/B vs HP 8662/63 640 MHZ

REF"

appears in the table of file names. Move the cursor until it encompasses the file name and press the Load File softkey. (This test file allows a reference HP 8642A or HP 8642B even though "HP 8662/63" is in the title.)

When the file has been loaded, press the DONE softkey.

Spectral Purity Tests for Options 005 and 006 55

Page 62

Calibration

Press the

NOTE

This file has been set up specifically to measure the HP 8642A and HP 8642B Signal Generators and all entries in the Define Measurement Parameter Table have been set for best measurement accuracy for these sources. It is assumed that the System's HP 8642A or HP 8642B is in the System's Configuration Table.

DONE|

softkey to select the Main Software Level menu.

Model 3048A

6. Press the

NOISE INPUT

FROM HP JS61A ,

SOURCE OUTPUT I

(REAR PANEL)!

HP 11848A'

PHASE NOISE

INTERFACE

New Msrmnt

softkey.

Connect the instruments as shown on the on-screen connection diagram and in Figure 37. If an

HP 8642A or 8642B Signal Generator is used as the second RF source, set its RF output for 640 MHz CW at +6 dBm.

HP 3561A DYNAMIC

SIGNAL ANALYZER

SECOND HP 8642A OR HP 8642B

SIGNAL GENERATOR

HP 8662A OR HP 8663A SYNTHESIZED SIGNAL GENERATOR

FIRST HP 8642A OR HP 8642B

SIGNAL GENERATOR

Figure 37. Spectral Purity Tests for Options 005 and 006 Setup

Press the | Proceed softkey. The measurement should proceed automatically without error messages.

If the reference source is an HP 8662A Option 003 or HP 8663A Option 003, the measured noise should be similar to that shown in Figure 38 and should be less than -134 dBc at 20 kHz offset or -144 dBc at 100 or 200 kHz offset. If the reference source is an HP 8642A or HP 8642B, subtract 3 dB from the measurement results; the limits should then be as previously stated.

Noise Limit for 100 or 200 kHz Offset:

56 Spectral Purity Tests for Options 005 and 006

Noise Limit for 20 kHz Offset:

-134 dBc

-144 dBc

Page 63

Model 3048A Calibration

HP TEST BG42R/B VS.

ChpJ 304BH Carrier: 640.E+6

-10

-20

-30

-40

-50

-G0

-70

-80

-90

-100

-1 10

-120

-130

-140

-150

-160

-170

—_J 1 l—L. ■ 1 1-1- 1 1 1..J-

10 100 IK 10K 100K

I t C-f) CdBc/Hz] vs i [Hz]

8663/63 RBS NOISE ®

Hz 21 Jan 1S8B 16:37

1 III

*•*.

1 1 1-1-

i iii

i_. .i it

640 MHz 4G - 16:

1 III

1 111,

1M 10M

43:

40M

Figure 38. Typical Spectral Purity Tests Results with HP 8662A Reference Source

Spectral Purity Tests for Options 005 and 006 57

Page 64

Model 3048A Calibration

Appendix A: Block Diagram and System Troubleshooting

BLOCK DIAGRAM

The foldout at the back of this manual is a block diagram of the HP 11848A Phase Noise Interface. When calibrating the System, the diagram helps to visualize what circuit functions are being tested.

It is also very useful when running the HP 11848A Control feature which is required in several of

the tests. The HP 11848A Control feature permits arbitrary control over all programmable circuits; the Block Diagram documents those circuits. For more information about the Block Diagram (such as theory of operation), refer to the HP

SYSTEM TROUBLESHOOTING

The tests described in this manual can often assist in isolating System faults down to a System device.

Some aspects of the main software tests as they apply to isolating faulty System devices are described in the following list.

11848A

Service Manual.

NOTE

A Diagnostic program for troubleshooting Noise Interface is supplied on a separate mass media disc. The Diagnostic program is independent of the main

to use the main software programs until they point to the Interface as the faulty System device. The Diagnostic program can then be loaded to

troubleshoot the Interface

Calibrate System. A series of transfer function measurements are made on various signal paths in

the Interface. The measurement data is stored as calibration factors which the controller uses (either directly or in more involved calculations) to correct the measured phase noise data whenever that signal path is used. Normally the Calibrate System program is invoked only for the annual System calibration or when the Interface has been repaired. Any difficulties encountered when the calibration program is being run may point to the Interface. For example, a catastrophic failure of a high-pass filter in the

Interface will generate data that is too far out of limits to be accepted as a legitimate transfer function;

the program will then abort the measurement.

Performance Tests. To verify that the system meets its published specifications, a series of Performance Tests can be run. The failure of a test may contain enough clues to point to a failure

in the Interface.

Internal Adjustments. Often small out-of-specification results of the Performance Tests or Functional Checks can be corrected by means of adjustments, particularly if the condition is due to a dc offset

voltage that is out of limits.

Functional Checks. These tests are an extension of the Performance Tests that test the general

operational integrity of the Interface Diagnostic program are similar to the Functional Checks, but they attempt to diagnose the failure in addition to simply indicating out-of-limits data.)

itself.

Refer to the HP 11848A Service Manual.

The test limits are generally loose. (The tests in the

specifically

software,

the HP

and it is usually more efficient

11848A

Phase

HP 11848A Control. Arbitrary and complete control of the programmable functions of the Interface

from the controller keyboard is provided by the HP 11848A Control program. A single display contains all the Interface state information. Because of the compactness of the state information, you should consult the HP the Diagnostic program is similar to this program.)

Troubleshoot Mode. When the Troubleshoot Mode (a subset of Test Mode) is enabled, information beyond simple error messages can be invoked. For example, tests can be aborted to the HP 11848A Control mode which shows the Interface state when the abort occurred.

3048A

Reference Manual when running the program. (The keyboard control feature of

Appendix A: Block Diagram and System Troubleshooting A-l

Page 65

Calibration Model 3048A

Switches on tlhe Block Diagram are shown in

their HP-IB preset state. At Interface turn-on with no controller connected, the power-up state is the same as the HP-IB preset state except:

a. ATTEN 1 is set to an open-circuit

(non-programmable) state, and

b. the switches of cluster S5 through S8 are

all open.

Assemblies A6, A8, and A9 are controlled as

follows:

State

Control Line

The transfer function of GAIN 2 also has a

lead-lag response as follows:

33.5 kHz

6 dB

67 kHz

3. The transfer function of Lag-Lead Network 1 is as follows:

67 kHz

26 dB

3.35 kHz

To this transfer function is added a

programmable lag-lead with the following poles

and zeros:

Lag-Lead

Number

Pole

Frequency

Zero

Frequency

Attenuation

L17 L18

L17,

L18

5. The transfer functions of Lag-Lead Network 2 on A4 and the Lag-Lead Network on A3 are both as follows:

3.35 kHz

Off Off On

On On

Off

On Off Off

20 dB

33.5 kHz

The passband gain of the High-Pass Filters is 2 (as measured from TP17 to the respective filter

output). The gain settings of the GAIN 3

amplifier and attenuator include the passband gain of the High-Pass Filters.

0 1 2 3 4 5 6 7

4.82 Hz

8.01 Hz

9.17 Hz

9.68 Hz

9.95 Hz

40.1 Hz

115.9 Hz 306 Hz 784 Hz

1.985 kHz

5.00 kHz

12.58 kHz

6dB 14 dB 22 dB 30 dB

38 dB 46 dB

54 dB 62 dB

Block Diagram Notes

A-2 Appendix A: Block Diagram and System Troubleshooting

Page 66

Model 3048A Calibration

Appendix B: HP 8662A or HP 8663A 640 MHz Spectral Purity Test

DESCRIPTION

This test measures the absolute noise floor of the System including the contributions of two 640 MHz reference sources (a combination of HP 8662A Option 003 and/or HP 8663A Option 003) in a normal phase-lock-loop, phase-noise measurement. Tuning is via the electronic frequency control (EFC) port of one of the 640 MHz sources.

NOTE

This test should not be confused with the Spectral Purity Tests for Options

001 and

RF output. This test measures the absolute phase noise on the low-phasenoise, rear-panel 640 MHz reference output. Also note that the two sources (HP 8662A or HP 8663A) must have the low phase-noise option (Option

003). This test is intended to be run when the Spectral Purity Test for Options

003 and 004 fails. If that test fails but this test passes, the failure is in one of the HP is in one of the HP 8662As or HP 8663As.

002.

That test measures the

11729C

Carrier Noise Test Sets. If this test

absolute

phase noise on the front-panel

also

fails, the failure

EQUIPMENT

Carrier Noise Test Set. This test requires a low-noise amplifier to increase the power level of one of the 640 MHz sources enough to adequately drive the L port of the RF phase detector in the Interface. An amplifier in the HP 11729C Carrier Noise Test Set ideally fills this need.

Printer. This test will run without the presence of a printer in the System's Configuration Table. However, it is recommended that the test be run with a printer.

Reference Signal Generator. A second HP 8662A Option 003 or HP 8663A Option 003 Synthesized

Signal Generator is required in addition to the one in the System.

RF Spectrum Analyzer. The System collects data to 100 kHz offsets with the HP 3561A. Data to 40

MHz offsets requires, in addition, an RF spectrum analyzer. Any supported RF spectrum analyzer can be used in this test. However, all specified effects are covered with the HP 3561 A. An RF analyzer is needed only if informational data beyond 100 kHz is desired.

PROCEDURE

The Noise Floor Test should be run before running this test.

Press the Define Msrmnt softkey. This softkey appears at the Main Software Level menu.

Press the Test Files softkey.

Press the |Next

Page|

softkey until the file name

REF"

appears in the table of file names. Move the cursor until it encompasses the file name and

press the Load

File|

softkey.

"HP

TEST HP 8662/63 vs HP 8662/63 ABS 640Mz

NOTE

This file has been set up specifically to measure the HP 8662A and HP 8663A Synthesized Signal Generators. All entries in the Define Measurement Parameter Table have been set for best measurement accuracy for these sources.

Appendix B: HP 8662A or HP 8663A 640 MHz Spectral Purity Test B-l

Page 67

Calibration

When the file has been loaded, press the DONE softkey.

6. Press the DONE softkey again to select the Main Software Level menu.

Model 3048A

SOURCE OUT

(REAR PANEL)

NOISE INPUT

FROM HP 3S61A

SOURCE OUTPUT

(REAR PANEL)

Press the

New Msrmnt

softkey.

8. Connect the instruments as shown in Figure B-l.

NOTE

The on-screen connection

diagram,

while showing technique, is incomplete. Also note that neither of the HP 8662As or HP 8663As in Figure B-l are under HP-IB control.

HP 3561A DYNAMIC

SIGNAL ANALYZER

SPECTRUM ANALYZER

the

general

measurement

Figure B-l. HP

FIRST

OR HP6$6M °" ^

SYNTHESIZED SIGNAL GENERATOR

8662A

or HP

8663A

640 MHi OUT

□ D 0 O

. □ 0 Q

D DO

□1

2 2

| o a a

: □ □

□ □

□ a

a a

oao

D'CID DDD a ODD a

DDD □

640 MHz Spectral Purity Test

SECOND

HP 8662A OR HP 8663A

SYNTHESIZED SIGNAL

GENERATOR

9. Press the Proceed softkey. The measurement should proceed automatically. The measured noise should be similar to that shown in Figure B-2 and should be within the limits given in the following table.

NOTE

// the beatnote frequency is too high, the System cannot tune the (EFC) source close enough to acquire phase

lock.

Various error messages on the

display warn of this condition. You must then manually adjust either 640 MHz source (in the HP 8662As or HP 8663As) to bring the difference frequency of the

and HP

8663A,

sources

within the

loop's

capture

the adjustment is located on the

range.

rear

panel and is

(For

the HP

labeled

8662A

"FINE FREQUENCY ADJUST".)

B-2 Appendix B: HP 8662A or HP 8663A 640 MHz Spectral Purity Test

Page 68

Model 3048A

Calibration

Frequency

At some frequency signals. When this

the

levels

the bases

the

table above

100 000

8662A Option

likelihood that specification.

are

003

3 dB

the

that

source alone.

Offset

(Hz)

100

1 000

10 000

100 000

offsets, is the

the

phase noise levels may be obscured by spurious

case,

the spurious signals.

noise level limits

higher than

or HP

8663A

noise level

case,

the

Noise Level

Actual

NOTE

(dBc)

Maximum

-54

-84

-104

-118

-142

-154

estimate the phase noise level by

for

the

published specification

Option

003.

This is

each source

combined noise

offsets

because

similar

is 3 dB

1000,

of the

and

higher than either

averaging

000,

and

for the HP

increased

to the

HP TEST 8662/63

Chp3 3048H Carrier: E40.E+6

Figure

8662/63 RBSOLUTE

100

IK 10K 100K

C-f)

CdBo/HzD

B-2.

Typical Spectral Purity Tests Results

Hz 20 Jan 138B

640 MHz REF.

vs f lHz.1

15:1B:04 - 15:23:23

NOISE

40M

Appendix B: HP 8662A

or HP

8663A 640 MHz Spectral Purity Test

B-3

Page 69

REGIONAL SALES AND SERVICE OFFICES

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Page 70

Residual Phase Noise

and AM Noise

Measurement Techniques

HEWLETT®

PACKARD

Printed in USA

Page 71

Page 72

Residual Phase Noise

and AM Noise

Measurement Techniques

El HEWLETT

"um PACKARD

HP Part No. 03048-90059

Printed in USA November 1994

Edition A.0.0

Page 73

Notice

The information contained in this document is subject to change without notice. Hewlett-Packard makes no warranty of any kind with regard to this material, including

but not limited to, the implied warranties of merchantability and fitness for a particular purpose. Hewlett-Packard shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing, performance, or use of this material.

1400 Fountaingrove Parkway, Santa Rosa, CA 95403-1799, USA

Page 74

Certification

Hewlett-Packard Company certifies that this product met its published specifications at the time of shipment from the factory. Hewlett-Packard further certifies that its calibration measurements are traceable to the United States National Institute of Standards and

Technology, to the extent allowed by the Institute's calibration facility, and to the calibration

facilities of other International Standards Organization members.

Warranty

This Hewlett-Packard instrument product is warranted against defects in material and

workmanship for a period of one year from date of shipment. During the warranty period, Hewlett-Packard Company will, at its option, either repair or replace products which prove to

be defective.

For warranty service or repair, this product must be returned to a service facility designated by Hewlett-Packard. Buyer shall prepay shipping charges to Hewlett-Packard and Hewlett-Packard shall pay shipping charges to return the product to Buyer. However, Buyer shall pay all shipping charges, duties, and taxes for products returned to Hewlett-Packard from another country.

Hewlett-Packard warrants that its software and firmware designated by Hewlett-Packard for use with an instrument will execute its programming instructions when properly installed on that instrument. Hewlett-Packard does not warrant that the operation of the instrument, or software, or firmware will be uninterrupted or error-free.

LIMITATION OF WARRANTY

The foregoing warranty shall not apply to defects resulting from improper or inadequate maintenance by Buyer, Buyer-supplied software or interfacing, unauthorized modification or misuse, operation outside of the environmental specifications for the product, or improper site preparation or maintenance.

NO OTHER WARRANTY IS EXPRESSED OR IMPLIED. HEWLETT-PACKARD SPECIFICALLY DISCLAIMS THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

EXCLUSIVE REMEDIES

THE REMEDIES PROVIDED HEREIN ARE BUYER'S SOLE AND EXCLUSIVE REMEDIES. HEWLETT-PACKARD SHALL NOT BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, WHETHER BASED ON CONTRACT, TORT, OR ANY OTHER LEGAL THEORY.

Assistance

Product maintenance agreements and. other customer assistance agreements are available for

Hewlett-Packard products.

For any assistance, contact your nearest Hewlett-Packard. Sales and Service

Office.

Page 75

Safety Symbols

The following safety symbols are used throughout this manual. Familiarize yourself with each of the symbols and its meaning before operating this instrument.

CAUTION The CAUTION sign denotes a hazard. It, calls attention to a procedure which, if

not, correctly performed or adhered to, could result in damage to or destruction of the product or the user's work. Do not proceed beyond a CAUTION sign until the indicated conditions are fully understood and met.

WARNING The WARNING sign denotes a hazard. It calls attention to a procedure

which, if not correctly performed or adhered to, could result in injury to the user. Do not proceed beyond a conditions are fully understood and met.

DANGER The DANGER sign denotes an imminent hazard to people. It warns the

reader of a procedure which, if not correctly performed or adhered to, could result in injury or loss of life. Do not proceed beyond sign until the indicated conditions are fully understood and met.

WARNING

sign until the indicated

DANGER

Page 76

General Safety Considerations

WARNING ■ These servicing instructions are for use by qualified personnel only. To

avoid electrical shock, do not perform any servicing unless you are qualified to do so.

■ The opening of covers or removal of parts is likely to expose dangerous voltages. Disconnect the instrument from all voltage sources while it is being opened.

■ The power cord is connected to internal capacitors that may remain live for five seconds after disconnecting the plug from its power supply.

■ This is a Safety Class 1 Product (provided with a protective earthing ground incorporated in the power cord). The mains plug shall only be

inserted in a socket outlet provided with a protective earth contact. Any interruption of the protective conductor inside or outside of the instrument is likely to make the instrument dangerous. Intentional

interruption is prohibited.

■ For continued protection against fire hazard, replace fuse only with same type and ratings, (type nA/nV). The use of other fuses or materials

is prohibited.

WARNING ■ Before this instrument is switched on, make sure it has been properly

grounded through the protective conductor of the ac power cable to a socket outlet provided with protective earth contact.

Any interruption of the protective (grounding) conductor, inside or outside the instrument, or disconnection of the protective earth terminal can result in personal injury.

■ Before this instrument is switched on, make sure its primary power

circuitry has been adapted to the voltage of the ac power source.

Failure to set the ac power input to the correct voltage could cause damage to the instrument when the ac power cable is plugged in.

Page 77

Acknowledgements

This manual is based on the technical paper "Residual Phase Noise and AM Noise Measurement Techniques" by Thomas R. Faulkner and Robert E. Temple.

Page 78

Contents

General Information

What is residual two-port noise? 1-1 Why are residual and AM noise measurements important? 1-2 HP 3048A Description 1-3

Residual Phase Noise Measurement

Basic Phase Noise Measurement Theory 2-1

Region of Validity of £(f) = S^(f)/2 2-2

Conversion Between S^(f) and S(y(f) 2-3

Residual Phase Noise Measurement: Basic Assumptions 2-5 Steps for Making Residual Phase Noise Measurements 2-6 Choosing a Calibration Method 2-7

Method 1: User entry of phase detector constant 2-7 Method 2: Measured +/-dc peak voltage 2-8 Method 3: Measured Beatnote 2-9 Method 4: Double-Sided Spur 2-10

Method 5: Single-Sided Spur 2-11 Calibration and Measurement General Guidelines 2-12 Calibration and Measurement Procedures 2-14

Method 1: User entry of phase detector constant 2-14

Method 2: Measured +/- DC Peak Voltage 2-17

Method 3: Measured Beatnote Method > 2-18

Method 4: Double-sided Spur 2-21

Method 5: Single-Sided Spur Method 2-24 Residual Phase Noise Measurement Examples 2-27

System Noise Floor Measurement 2-27

Initial Setup 2-27 Conditions 2-28 Results ; 2-28

Amplifier Noise and Dynamic Noise Figure Measurement 2-30

Initial Setup 2-30 Conditions 2-31 Results 2-31

Measurement of a Device with Large Time Delay (r) 2-33

Initial Setup 2-33 Conditions 2-34 Results 2-35

Measurement of a Crystal Resonator 2-37

Initial Setup 2-37 Conditions 2-37

Measuring the Noise Floor of the Test Setup 2-38

Measuring the Crystal Resonator 2-38 Results of the Setup Noise Floor Measurement 2-39 Results of the Crystal Resonator Measurement 2-39

Measurement of a Low-Noise Phase Modulator

;

2-42

Contents 1

Page 79

Initial Setup 2-42 Conditions 2-42 Results 2-43

Residual Noise of a Frequency Synthesizer 2-44

Initial Setup 2-45 Conditions 2-46 Results 2-46

Residual Noise of a Comb Generator Multiplier 2-48

Initial Setup 2-48 Conditions 2-49 Results 2-49

Measurement of a Device Using an External Phase Detector 2-51

Initial Setup 2-51 Conditions 2-51 Results 2-52

AM-Source Noise Measurement

AM-Noise Measurement Theory of Operation 3-1

Basic Noise Measurement 3-1 Phase Noise Measurement 3-1

Amplitude Noise Measurement 3-2 AM Noise Measurement System Block Diagram 3-2 AM Detector 3-3

AM Detector Specifications 3-3

AM Detector Considerations 3-3 Steps for Making AM Noise Measurements ■ 3-4 Choosing a Calibration Method 3-6

Method 1: User entry of phase detector constant 3-6

Method 1, Example 1 3-6 Method 1, Example 2 3-6 Method 2: Double Sided Spur 3-7

Method 2, Example 1 3-7

Method 2, Example 2 3-7 Method 3: Single-Sided-Spur Method 3-7

Calibration and Measurement General Guidelines 3-8 Calibration and Measurement Procedures 3-9

Method 1: User Entry of Phase Detector Constant 3-9

Method 1, example 1 3-9 Method 1, Example 2 3-11 Method 2: Double-Sided Spur Method 3-12

Method 2, Example 1 3-12

Method 2, Example 2 3-13

Method 3: Single-Sided-Spur Method 3-15

Examples of AM Noise Measurements 3-17

Measurement of a Source with AM 3-17

Initial Setup 3-17

Conditions 3-18

Results . 3-18

Measurement Of A Source Without, AM 3-20

Initial Setup 3-20

Conditions 3-20

Results 3-21

Measurement of a Microwave Source without AM Modulation 3-23

Initial Setup ., 3-23 Conditions 3-24

Contents-2

Page 80

Results 3-24

Baseband Noise Measurements

Measurement Considerations 4-1 Steps for Making Baseband Noise Measurements 4-1

A. Calculation of Source Noise Attenuation

Source Noise Attenuation versus Carrier Offset and Time Delay A-l

Noise Figure Versus Dynamic Noise Figure

Single-Sided Spur

Carrier-to-Sideband Modulation Equations

AM Carrier-to-Modulation Sideband Ratio D:l

Example D-l

M Carrier-to-Modulation Sideband Ratio D-l

Example D-l

FM Carrier-to-Modulation Sideband Ratio D-2

Example D-2

Common Equipment Used in RF Noise Measurements

Sources E-l Spectrum Analyzers E-J Modulation Analyzers E-2

Power Meters E-2 Diode Detectors E-2 AM Detector E-2 DC Block E-2 Attenuators E-3 Amplifiers E-3 Phase Shifters E-3 0° Power Splitters E-4 Couplers E-4 Instrument Suppliers E-4

F. Components of the Phase Noise Accessory Kits

Components for Residual Measurements F-l Miscellaneous Components F-3

Cables F-3

Adapters F-4

Case Layout F-5

G. HP 3048A Options KOl, K02, K21, K22, and K23 Specifications

HP 70428A Option KOl Tune Volt Supply G-l HP 70427A Option K02 Balun G-l HP 3048A Option K21 AM Detector Filter G-2

HP 3048A Option K22 AM Dual RF Amplifier G-3

HP 3048A Option K23 AM DC Blocking Filter G-4

Contents-3

Page 81

Figures

1-1. Additive Noise Components 1-1 1-2. Multiplicative Noise Components 1-2 1-3. HP 3048A Block Diagram 1-4

2-1.

Double-Balanced Mixer Used as a Phase Detector 2-1

2-2.

Region of Validity of £(f) =

2-3.

S?i(f)/2: 1/2 Spectral Density of Phase Fluctuation 2-4

2-4. S„(f): Spectral Density of Phase Fluctuation 2-4 2-5 2-5 2-6 2-5 2-7.

Measuring Power at Phase Detector R Port 2-14

2-8.

Phase Detector Sensitivity 2-15

2-9.

Measuring Power at Phase Detector L Port 2-16 2-10. Connection to Optional Oscilloscope for Determining Voltage Peaks 2-17 2-11.

Measuring Power from Splitter 2-18 2-12. Calibration Source Beatnote Injection 2-20 2-13.

Double-Sided Spur Calibration Setup 2-21 2-14. Measuring Carrier-to-sideband Ratio of the Modulated Port 2:22 2-15.

Measuring Carrier-to-sideband Ratio of the Non-modulated Port 2-23 2-16. Single-Sided Spur Calibration Setup 2-24 2-17.

Carrier-to-sideband Ratio of the Modulated Signal 2-25

2-18.

Carrier-to-spur Ratio of the Non-modulated Signal 2-25 2-19. User Entry of Phase Detector Constant Calibration Setup 2-27 2-20. User Entry of Phase Detector Constant Measurement Setup 2-27 2-21.

System Noise Floor Results Graph 2-29 2-22. Dynamic Noise Figure Measurement, Setup 2-30 2-23.

Dynamic Noise Figure Results Graph 2-32 2-24. Time Delay Measurement Setup 2-33 2-25.

Graph of Source Decorrelation 2-34 2-26. Time Delay Results Graph 2-36 2-27.

Crystal Measurement Setup 2-37 2-28.

Noise-Floor Measurement, Test, Setup 2-38 2-29. Noise Floor Measurement Results 2-40 2-30. Noise Floor Measurement Results 2-41 2-31.

Low Noise Phase Modulator Measurement, Setup 2-42 2-32. Phase Modulator Noise HP 8640B Source 2-44 2-33.

Frequency Synthesizer Measurement Setup 2-45 2-34. Residua] Noise: Two HP 8663A Synthesizers 2-47 2-35.

Residual Noise of Step-Recovery Diode Setup 2-48 2-36. Residual Noise: Step Recovery Diode 2-50 2-37.

External Phase Detector Setup 2-51 2-38.

HP 3325A Fractional Divider/Phase Detector Measurement Results 2-53

3-1.

System Block Diagram 3-2

3-2. AM Detector Schematic 3-3 3-3.

AM Noise Measurement Setup 3-9

3-4. AM Noise Calibration Setup 3-9 3-5.

AM Detector Sensitivity Graph 3-10

S^(f)/2

2-3

Contents-4

Page 82

3-6. AM Noise Measurement Setup 3-11

3-7. Modulation Sideband Calibration Setup . 3-11

3-8.

AM Noise Measurement Setup 3-12

3-9. Measuring the Carrier-to-Sideband Ratio 3-12

3-10. Measuring the Calibration Constant 3-13 3-11.

AM Noise Measurement Setup 3-13 3-12. Measuring Power at the AM Detector 3-13 3-13.

Measuring Carrier-to-Sideband Ratio 3-14 3-14. Measuring the Calibration Constant 3-14 3-15.

AM Noise Measurement Setup Using Single-Sided-Spur 3-15 3-16. Measuring Relative Spur Level 3-15 3-17. Measuring Detector Sensitivity 3-15 3-18. AM Noise Measurement Setup for a Source with AM 3-17 3-19. AM Modulation Measurement Results 3-19 3-20. Source Without AM Measurement Setup 3-20

3-21.

Source Without AM Modulation Measurement Results 3-22 3-22. Microwave Source Without AM Setup 3-23 3-23.

Microwave Source Without AM Measurement Results 3-25

4-1.

Baseband Noise Measurement Block Diagram 4-1

4-2.

S,,(dBv/Hz) versus f (Hz) 4-2

F-1.

Single-Sided Spur Calibration Setup for Residual Measurement F-1

F-2.

Single-sided Spur Calibration Setup for AM Noise Measurement F-2

F-3.

HP 11826A/B/C Small Case Layout F-5

F-4.

HP 11826A/B/C Large Case Layout F-6

Contents-5

Page 83

General Information

What is residual two-port noise?

Residual two-port noise is the noise added to a signal when the signal is processed by a two-port device. Such devices include: amplifiers, dividers, filters, mixers, multipliers,

phase-locked loop synthesizers and any other two-port electronic network. Residual two-port noise contains both AM and $M components.

Residual two-port noise is the sum of two basic noise mechanisms:

Additive noise: This noise is generated by the two-port device, at or near the signal

frequency, which adds in a linear fashion to the signal.

DEVICE

UNDER TEST

SOURCE:

<s>

NOISELESS

SOURCE

Figure 1-1. Additive Noise Components

Multiplicative noise: This noise has at least two mechanisms. The first is an intrinsic, direct,

phase modulation with a j spectral density, the origin of which is unknown. The second, in the case of amplifiers or multipliers, is noise which may modulate an RF signal by the multiplication of baseband noise with the signal. This mixing is due to non-linearities in the two-port network. The baseband noise may be produced by the active devices of the internal network, or may come from low-frequency noise on the signal or power supply.

RF NOISE AROUND

THE SIGNAL FREQUENCY

RF NOISE ADDED

TO THE SIGNAL

General Information 1-1

Page 84

SOUF

DEVICE

UNDER TEST

ICE

-JK—

BASE BAND NOISE

MIXED AROUND

THE SIGNAL

NOISELESS

SOURCE

Figure 1-2. Multiplicative Noise Components

Why are residual and AM noise measurements important?

■ In recent years it has become apparent to primary contractors that to ensure overall system

noise performance, residual noise must be specified for all subsystems.

■ The absolute noise of an oscillator is set by the residual noise of the active device, the residual noise of the resonator, and the bandwidth of the resonator.

■ Oscillator noise is degraded by the residual noise of all the devices that follow it: amplifiers, dividers, filters, mixers, multipliers, phase-locked loops, synthesizers, and so forth.

■ AM noise is important in generators for residual phase-noise testing or adjacent-channel receiver testing.

BASE BAND

NOISE

■ Any active or non-linear device produces some level of AM to $M noise conversion. This AM can contribute to the residual phase noise. This includes AM noise in phase detectors.

■ When troubleshooting unsatisfactory phase noise performance, it, may be necessary to measure both the AM noise and the residual the problem.

1-2 General Information

4>M

noise of the system components to locate

Page 85

HP 3048A Description

The HP 3048A provides you standard process for measuring phase noise. It allows you to measure sources of many types with a flexible system configuration.

The HP 3048A Phase Noise Measurement System includes the following instruments and accessories.

■ The HP 11848A Phase Noise Interface, an interface box specifically designed for high performance phase noise measurements. The HP 11848A supports several measurement techniques for phase noise and AM noise measurement. Built into the interface are phase detectors, amplifiers, filters, and switches necessary to measure phase noise over a frequency range of 5 MHz to 18 GHz. An input for an external phase detector outside the above mentioned frequency range is also provided. Internal sources are provided to allow the system to functionally check all of its signal handling circuits ensuring proper operation prior to making a measurement.

■ The HP 3561A Dynamic Signal Analyzer, a Fast Fourier Transform analyzer of a wide

frequency range (125 /<Hz to 100 kHz). The HP 3561A has built-in data averaging capabilities, large dynamic range, and fast measurement speed which make it ideal for quantifying demodulated phase noise (noise voltages).

■ Measurement software, a program that includes all drivers necessary to run both standard and optional instruments of the HP 3048A system.

■ Operator's Training, a training course that explains all of the operating modes and measurement techniques of the HP 3048A, when each technique is appropriate, and how to analyze the measured data.

General Information 1-3

Page 86

1-4 General Information

Figure 1-3. HP 3048A Block Diagram

Page 87

Residual Phase Noise Measurement

Basic Phase Noise Measurement Theory

Phase noise can be measured by demodulating the RF signal and analyzing it at baseband.

Doubly balanced mixer used as phase detector

V, Sin [27rfot+0(t)] >-

Low Pass

Filter

V. Sin [2xf t+90°] >■

s -M>

jt(U=^l=Ml

2 2K20

Demodulate RF signal and analyze at baseband

Measure spectral density of noise fluctuation

3. Calculate phase noise

Figure 2-1. Double-Balanced Mixer Used as a Phase Detector

because

10(t) I

M x 0(t)=V„(t) If [0(t)]<.2 rad

< .2rad

Residual Phase Noise Measurement 2-1

Page 88

A double-balanced mixer is used as a phase detector to demodulate the RF signal for baseband analysis.

When operated as a phase detector, two signals are input to the double-balanced mixer at the same frequency. The phase difference between the signals is adjusted to 90° (quadrature) to minimize the detector's sensitivity to AM fluctuations, and to maximize its sensitivity to phase fluctuations. Any phase fluctuations not common to both signals (for example, <p(t)) result in a voltage fluctuation proportional to the phase difference, provided the phase fluctuations are less than approximately 0.2 radians. This voltage output ;;„(t) is equal to the difference in phase fluctuations multiplied by the phase detector gain of the mixer,

KJ,,

in volts per radian.

The spectral density of the phase fluctuations, S^Cf), is calculated by measuring the spectral

density of voltage fluctuations, S„(f) with a baseband spectrum analyzer. S„(f) is then divided by the square of the phase detector constant (squared because of the power relationship of spectral density) which results in S^(f).

The single-sided phase noise £(f), can then be calculated from the spectral density of phase fluctuation phase fluctuations,

SJ,(I"),

(or frequency fluctuation,

<j>-(t),

are small relative to 1 radian.

S;,(f)

= f-xS^(f)) provided that, the mean square

Region of Validity of £(f) =

S^(f)/2

Because of the small-angle criterion, caution must be exercised when £(f") is calculated from the spectral density of the phase fluctuations. This plot (figure 2-2) of £(f) resulting from the phase noise of a free-running VCO illustrates the erroneous results that, can occur if the instantaneous phase modulation exceeds a small angle. Approaching the carrier, £(f) is obviously increasingly in error as it reaches a relative level of +45 dBc/Hz at a I Hz offset (45 dB more power at a 1 Hz offset, in a 1 Hz bandwidth, than the total power in the signal). The

-10 dB/decade line is drawn on the plot for an instantaneous phase deviation of 0.2 radians integrated over one decade of offset frequency. At approximately 0.2 radians the power in the higher-order sidebands of the phase modulation is still insignificant compared to the power in the first-order sideband, thus ensuring the validity of the calculation of £(f). Below the line, the plot of £(f) is correct; above the line, £(f) becomes increasingly invalid and S^(f) must be used to represent the phase noise of the signal.

2-2 Residual Phase Noise Measurement

Page 89

866-4B,

.4 aVERt*SE5 CRRRIER FRE->t? rgBE^Hz

EXT FM OFF,

864 QB

REF, 3dO KHZ PK DEV Fll

trip]

RPR 4

13.4fl/

14:8?

1Hz Lift CdBc

Figure 2-2. Region

Conversion Between

Other than S^(f), density ;/(t)

root

frequency fluctuations, Sj/(f).

is the

derivative

S„(f). The graph frequency modulation (FM) noise the FM noise versus

the

S^f) and

instability

<?i(t).

of the

the

offset from

of a

These

square root

on the

Hz] vi

Validity

of £(f) =

S;/(f)

signal may also

illustrated below

two

graphs

signal. Such a measurement

the

carrier

are

S/,(f)

is be

represented with a plot

from

indicates

very useful

iCHz] 4 0MH

S^(f)/2

S„(f) is

the

same data with figure

the

equal

power spectral density

of the

in the

design

of the

fxS.y/f) because

spectral density

of an

spectral

2-3 a

square

of the

FM system.

Residual Phase Noise Measurement

2-3

Page 90

-150

-l"50

•

lOHl

CONVERSION BETWEEN S»(f) AND Sv(f)

StipL'ir'3t»"t>UT"

i ' ■

■' 1—1 ill i i ■ 11 i i_

tin CdBc'Hrj vs fCH:}

' "I L.

ion

4QNHz

Figure 2-3. S

c-oe

c*oe

^V>i

t-Ji

c»ee

t-«3

' i ■ i i i

IOHI

j,(f)/2:

1/2 Spectral Density of Phase Fluctuation

36~^

VS 8350. 83525H

P0T31RE

NOJSC n.OC*» LtnlT 18 TO 4a : M;

lee ik ie< IPOK IM

' ' I ■ i i t i i i i I.I i

I I I L.

SOPT CSv(f) (Hz-2 Hi]) VS <CHr]

10M

«OMHx

Figure 2-4. S;,(f): Spectral Density of Phase Fluctuation

2-4 Residual Phase Noise Measurement

Page 91

Residual Phase Noise Measurement: Basic Assumptions

■

The

source noise

for

the

frequency-offset range

each

of the two

interest. (This assumption will

phase-detector paths

correlated

at the

examined more closely.)

phase detector

■ Correlated phase noise

■ Source AM noise AM noise rejection.

Given these assumptions, inputs

of the

the

DUT will

the

DUT

is a

result will

identical,

that If a more precise determination two DUTs. The data from each to give

can be

the

be the

can

concluded

noise

phase detector, then

measured.

frequency translating device, then

sum

assumed that

at the

small. A typical mixer-type phase detector only

if a

SOURCE

of the

each

noise from each DUT.

that one

of the

phase detector will cancel.

device-under-test (DUT)

all of the

source noise will cancel

DEVICE

—*■

UNDER

TEST

DETECTOR

POWER SPLITTER

PHASE

Figure 2-5.

one

For

the

noise

each

of the

individual DUTs.

DUTs

is at

least

required, a third DUT must

three experiments

placed ahead

DUT must

most applications,

half

the

3 dB

can

BASE BAND ANALYSIS

be put in

measured result

better than be

measured against

then

has

either

and

only

if the

the

processed

about

20 to

30 dB

of the two

the

residual noise

each path.

or 3

measured result.

by the

DUTs

dB less.

the

The

are

All

other

system

SOURCE

■

DEVICE

UNDER

TEST

DETECTOR

POWER SPLITTER

DEVICE

UNDER

TEST

Figure

PHASE

2-6.

BASE BAND ANALYSIS

Residual Phase Noise Measurement 2-5

Page 92

Steps for Making Residual Phase Noise Measurements

■ Connect the system hardware and load/run the software.

■ Measure the system calibration data. The system calibration data is the correction data for all the signal paths in the interface box.

■ Main Menu—Select the type of measurement to be made. All residual phase noise measurements will be "PHASE NOISE MEASUREMENT WITHOUT VOLTAGE CONTROL."

■ Establish parameters.

Source parameters '

a. Enter phase detector input frequency

Enter carrier frequency

c. Select internal or external phase detector (mixer)

d. Select calibration option

Measurement parameters

a. Enter start and stop frequencies for the measurement data

□ HP 3048A without RF analyzer: 0.01 Hz to 100 kHz D

HP 3048A with RF analyzer: 0.01 Hz to 40 MHz

Enter number of sweeps averaged on FFT analyzer

Plot parameters

a. Select graph type (usually "SINGLE SIDEBAND PHASE NOISE")

Select plotter type (if any)

c. Enter minimum and maximum Y-axis values (dBc)

d. Enter minimum and maximum X-axis values (Hz)

e. Enter a title

■ Make measurement.

Connect the DUT and external hardware

Measure calibration data by selected option

Measure noise data

■ Interpret, the measurement results.

2-6 Residual Phase Noise Measurement

Page 93

Choosing a Calibration Method

Method 1: User entry of phase detector constant

This calibration option requires that you know the phase detector constant for the specific

measurement to be made. The phase detector constant can be estimated from the source power levels or it can be determined using one of the other calibration methods.

Once determined, the phase detector constant can be entered directly into the system software

without going through a calibration sequence. Remember, however, that the phase detector constant is unique to a particular set of sources, the RF level into the phase detector, and the test configuration.

Advantages Easy method of calibrating the measurement system.

Requires little additional equipment, only an RF power meter to manually

measure the drive levels into the phase detector.

Fastest method of calibration. If the same power levels are always at the phase

detector (as in the case of leveled outputs) the phase detector sensitivity will always be essentially the same (within 1 or 2 dB). If this accuracy is adequate,

it is not necessary to recalibrate. Only one RF source is required. Quick method of estimating the phase detector constant and noise floor to

verify other calibration methods and check available dynamic range.

Disadvantages Least accurate of the calibration methods.

Does not take into account, the amount, of power at harmonics of the signal.

Does not take into account the power which may be generated by spurious

oscillations, causing the power meter to measure more power than is at the

distinct phase-detector frequency.

Residual Phase Noise Measurement 2-7

Page 94

Method 2: Measured +/- dc peak voltage

This technique requires you to adjust off of quadrature to both the positive and the negative peak output of the Phase Detector. This is done by either adjusting the phase shifter or the frequency of the source. An oscilloscope or voltmeter is optional for setting the positive and negative peaks.

Advantages Easy method of calibrating the measurement system.

This calibration technique can be performed using the HP 3561A. Fastest method of calibration. If, for example, the same power levels are

always at the phase detector, as in the case of leveled or limited outputs, the phase detector sensitivity will always be essentially equivalent (within 1 or 2 dB).

Recalibration becomes unnecessary if this accuracy is adequate. Only one RF source is required. Measures the phase detector gain in the actual measurement configuration.

Disadvantages Has only moderate accuracy compared to the other calibration methods.

Does not take into account the amount, of phase detector harmonic distortion relative to the measured phase detector gain, therefore, the phase detector must operate in its linear region.

Requires manual adjustments to the source and/or phase shifter to find the phase detector's positive and negative output peaks. The system will read the value of the positive and negative peak and automatically calculate the mean of the peak voltages which is the the phase detector constant used by the system.

2-8 Residual Phase Noise Measurement

Page 95

Method 3: Measured Beatnote

This calibration option requires that one of the input frequency sources be tunable such that a beatnote can be acquired for the two sources. For the system to calibrate, the beatnote frequency must be within the ranges shown in the table below. (You should also note that for beatnote frequencies below 20 Hz, it will take the system longer to determine the calibration constant.)

Carrier

Frequency

< 95 MHz > 95 MHz

Beatnote

Frequency Range (fe)

1 Hz < fB < 1 MHz

1 Hz < fB < 20 MHz

Advantages Does not require an RF spectrum analyzer.

Simple method of calibration.

Disadvantages It does not take into account the harmonics of the phase detector and all

non-linearities thereof when using the HP 3048A. It requires two RF sources separated by 1 Hz to 40 MHz at the phase detector.

The calibration source output power must be manually adjusted to the same level as the power splitter output it replaces (requires a power meter).

It is less accurate than either the phase modulation method or the single sided spur method.

Residual Phase Noise Measurement 2-9

Page 96

Method 4: Double-Sided Spur

This calibration option has the following requirements:

■ One of the input frequency sources must be capable of being frequency or phase modulated.

■ The resultant sideband spurs from the FM or $M modulation must have amplitudes that are > —

100 dB and <-20 dB relative to the carrier amplitude.

■ The offset frequency or modulation frequency must be between 20 Hz and 100 kHz if only the HP 3561A analyzer is configured in the system, or between 20 Hz and 20 MHz if an RF spectrum analyzer is also configured in the system.

Advantages Requires only one RF source.

Calibration is done under actual measurement conditions so all non-linearities are calibrated out. Because the calibration is performed under actual measurement conditions, the Double-sided Spur Method and the Single-sided

Spur Method are the two most accurate calibration methods.

Disadvantages Requires an RF spectrum analyzer for manual measurement of

Requires audio calibration source.

Requires a phase modulator which operates at the desired carrier frequency.

(Most phase modulators are narrow-band devices, therefore a wide range of

test frequencies will require multiple phase modulators.)

<i>M

sidebands.

2-10 Residual Phase Noise Measurement

Page 97

Method 5: Single-Sided Spur

This calibration option has the following requirements:

■ A third source to generate a single-sided spur.

■ An external power combiner (or adder) to add the calibration spur to the frequency carrier under test. The calibration spur must have an amplitude >-100 dB and <-20 dB relative to

the carrier amplitude. The offset frequency of the spur must be >20 Hz and <20 MHz.

■ A spectrum analyzer or other means to measure the single-sided spur relative to the carrier

signal.

You will find that the equipment setup for this calibration option is similar to the others except that an additional source and a power splitter have been added so that the spur can be summed with the input carrier frequency.

Advantages Calibration is done under actual measurement conditions so all non-linearities

and harmonics of the phase detector are calibrated out.

The Double-sided Spur Method and the Single-Sided Spur Method are the two

most accurate methods. Broadband couplers with good directivity are available, at reasonable cost, to

couple-in the calibration spur.

Disadvantages Requires two RF sources that must be between 20 Hz and 100 kHz if only an

HP 3561A analyzer is configured in the system, or between 20 Hz and 20 MHz if an RF spectrum analyzer is configured in the system.

Requires an RF spectrum analyzer for manual measurement of the signal-to-spur ratio and the spur offset frequency.

Residual Phase Noise Measurement 2-11

Page 98

Calibration and Measurement General Guidelines

Read This The following general guidelines should be considered when setting up and

making a residual two-port phase noise measurement.

For residual phase noise measurements, the source noise must, be correlated.

a. The phase delay in the paths between the power splitter and the phase detector must

be kept to a minimum when making residual noise measurements. In other words, by keeping the cables between the phase detector and power splitter short, r will be small. The attenuation of the source noise is a function of the carrier offset frequency, and the delay time (r) and is equal to:,

Attenuation (dB) =

where : f = carrier offset frequency

Note

For / = l/(27rr) the attenuation of the source is 0 dB.

For / < l/(27rr) the source noise is attenuated at the rate of 20 dB per decade. For piq there is 6 dB gain. See appendix A.

The source should also have a good broadband phase noise floor because at sufficiently

large carrier offsets it will tend to decorrelate when measuring components with large

delays. A source with a sufficiently low noise floor may be able to hold an otherwise

impossible measurement within the region of validity. Examples of sources which best meet these requirements are the HP 8640B and HP 8642A/B.

The source used for making residual phase noise measurements must be low in AM noise

because: a. Source AM noise can cause AM to b.

Mixer-type phase detectors only provide about 20 to 30 dB of AM noise rejection in a $M

noise measurement.

It is very important that all components in the test setup be well shielded from RFI.

Unwanted RF coupling between components will make a measurement setup very vulnerable to external electric fields around it. The result may well be a setup going out of quadrature simply by people moving around in the test setup area and altering surrounding electric fields. A loss of quadrature stops the measurement.

20 log

7r = 3.14159

r = time delay (sec.)

4>M

conversion in the DUT.

|2sin(;r x f x r)\

When making low-level measurements, the best results will be obtained from uncluttered

setups. Soft, foam rubber is very useful for isolating the DUT and other phase-sensitive components from mechanically-induced phase noise. The mechanical shock of bumping the test set or kicking the table will often knock a sensitive residual phase noise measurement out of quadrature.

2-12 Residual Phase Noise Measurement

Page 99

When making an extremely sensitive measurement it is essential to use semi-rigid cable

between the components. The bending of a flexible cable from vibrations and temperature

variations in the room can cause enough phase noise in flexible connecting cables to destroy the accuracy of a sensitive measurement. The connectors also must be tight; a wrench is the

best tool.

6. When measuring a low-noise device, it is important that the source and any amplification, required to achieve the proper power at the phase detector, be placed before the splitter so

it will be correlated out of the measurement. In cases where this is not possible; remember

that any noise source, such as an amplifier, placed after the splitter in either phase detector path, will contribute to the measured noise.

An amplifier must be used in cases where the signal level out of the DUT is too small to

drive the phase detector, or the drive level is inadequate to provide a low enough system noise floor. In this case the amplifier should have the following characteristics:

a. It should have the lowest possible noise figure, and the greatest possible dynamic range.

The signal level must be kept as high as possible at all points in the setup to minimize

degradation from the thermal noise floor.

c. It should have only enough gain to provide the required signal levels. Excess gain

leads to amplifiers operating in gain compression, making them very vulnerable to multiplicative noise problems. The non-linearity of the active device produces mixing which multiplies the baseband noise of the active device and power supply noise around the carrier.

d. The amplifier's sensitivity to power supply noise and the power supply noise itself must

both be minimized.

Residual Phase Noise Measurement 2-13

Page 100

Calibration

and

Measurement Procedures

The following procedures use

Method

Connect circuit

User entry

shown

SOURCE

the

system noise floor measurement

phase detector constant

figure 2-7

and

OPTIONAL LINE

STRETCHER

tighten

POWER METER

OR SPECTRUM ANALYZER

all

POWER SPLITTER

as an

connections.

HP 11848A

example.

PHASE OCTECTOR

Figure 2-7. Measuring Power

Phase Detector R Port

2-14 Residual Phase Noise Measurement