Agilent 33250A Service Guide

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Service Guide

Publication Number 33250-90011 (order as 33250-90100 manual set) Edition 2, March 2003

For Safety information, Warranties, and Regulatory information, see the pages following the Index.

Agilent 33250A 80 MHz Function / Arbitrary Waveform Generator

Agilent 33250A at a Glance

The Agilent Technologies 33250A is a high-performance 80 MHz synthesized function generator with built-in arbitrary waveform and pulse capabilities. Its combination of bench-top and system features makes this function generator a versatile solution for your testing requirements now and in the future.

Convenient bench-top features

• 10 standard waveforms

• Built-in 12-bit 200 MSa/s arbitrary waveform capability

• Precise pulse waveform capabilities with adjustable edge time

• LCD color display provides numeric and graphical views

• Easy-to-use knob and numeric keypad

• Instrument state storage with user-defined names

• Portable, ruggedized case with non-skid feet

Flexible system features

• Four downloadable 64K-point arbitrary waveform memories

• GPIB (IEEE-488) interface and RS-232 interface are standard

• SCPI (Standard Commands for Programmable Instruments) compatibility

Note: Unless otherwise indicated, this manual applies to all Serial Numbers.

The Front Panel at a Glance

1 Graph Mode/Local Key 2 Menu Operation Softkeys 3 Waveform Selection Keys 4 Knob 5 Modulation/Sweep/Burst Menus 6 State Storage Menu

Note: To get context-sensitive help on any front-panel key or menu softkey, press and hold down that key.

7 Utility Menu 8 Instrument Help Topic Menu 9 Output Enable/Disable Key

10 Manual Trigger Key (used for

Sweep and Burst only)

Cursor Keys

The Front-Panel Display at a Glance

Menu Mode

Numeric Readout

Mode

Information

Trigger

Information

Softkey Labels

Units

Output

Status

Graph Mode

To enter the Graph Mode, press the key.

Parameter

Name

Parameter

Value

Display Icon

Signal Ground

The softkey colors correspond

to the waveform parameters.

Front-Panel Number Entry

You can enter numbers from the front-panel using one of two methods.

Use the knob and arrow keys to modify the displayed number.

Use the numeric keypad and menu softkeys to select the units.

The Rear Panel at a Glance

External 10 MHz Reference Input Terminal

Internal 10 MHz Reference Output Terminal

3 RS-232 Interface Connector 4 External Modulation Input Terminal

Use the menu to:

• Select the GPIB or RS-232 interface (see chapter 2 in User’s Guide).

• Select the GPIB address (see chapter 2 in User’s Guide).

• Set the RS-232 baud rate, parity, and handshake (see chapter 2 in User’s Guide).

Input: External Trig/FSK/ Burst Gate Output: Trigger Output

6 GPIB Interface Connector 7 Chassis Ground

WARNING For protection from electrical shock, the power cord ground must not be

defeated. If only a two-contact electrical outlet is available, connect the instrument’s chassis ground screw (see above) to a good earth ground.

In This Book

Specifications Chapter 1 lists the function generator’s specifications.

Quick Start Chapter 2 prepares the function generator for use and

helps you get familiar with a few of its front-panel features.

Front-Panel Menu Operation Chapter 3 introduces you to the frontpanel menu and describes some of the function generator’s menu features.

Calibration Procedures Chapter 4 provides calibration, verification, and adjustment procedures for the function generator.

Theory of Operation Chapter 5 describes the block diagram and circuit-level theory related to the operation of the function generator.

Service Chapter 6 provides guidelines for returning your function generator to Agilent Technologies for servicing, or for servicing it yourself.

Replaceable Parts Chapter 7 contains a detailed parts list of the function generator.

Backdating Chapter 8 describes the differences between this manual and older issues of this manual.

Schematics Chapter 9 contains the function generator’s schematics and component locator drawings.

If you have questions relating to the operation of the Agilent 33250A, call 1-800-452-4844 in the United States, or contact your nearest Agilent Technologies Office.

If your 33250A fails within three years of purchase, Agilent will either repair or replace it free of charge. Call 1-877-447-7278 in the United States (and ask for “Agilent Express”) or contact your local Agilent Technologies Office.

Chapter 1 Specifications 13

Chapter 2 Quick Start

To Prepare the Function Generator for Use 21 To Adjust the Carrying Handle 22 To Set the Output Frequency 23 To Set the Output Amplitude 24 To Set a DC Offset Voltage 26 To Set the Duty Cycle 27 To Configure a Pulse Waveform 28 To View a Waveform Graph 29 To Output a Stored Arbitrary Waveform 30 To Use the Built-In Help System 31 To Rack Mount the Function Generator 33

Chapter 3 Front-Panel Menu Operation

Front-Panel Menu Reference 37 To Reset the Function Generator 39 To Select the Output Termination 39 To Read the Calibration Information 40 To Unsecure and Secure for Calibration 41 To Store the Instrument State 44 To Configure the Remote Interface 45

Chapter 4 Calibration Procedures

Agilent Technologies Calibration Services 49 Calibration Interval 50 Adjustment is Recommended 50 Time Required for Calibration 51 Automating Calibration Procedures 52 Recommended Test Equipment 53 Test Considerations 54 Performance Verification Tests 55 Internal Timebase Verification 60 AC Amplitude (high-impedance) Verification 61 Low Frequency Flatness Verification 62 0 dB Range Flatness Verification 63 +10 dB Range Flatness Verification 65 +20 dB Range Flatness Verification 66

Contents

Chapter 4 Calibration Procedures (continued)

Calibration Security 68 Calibration Message 70 Calibration Count 70 General Calibration/Adjustment Procedure 71 Aborting a Calibration in Progress 72 Sequence of Adjustments 72 Self-Test 73 Frequency (Internal Timebase) Adjustment 74 Internal ADC Adjustment 75 Output Impedance Adjustment 76 AC Amplitude (high-impedance) Adjustment 78 Low Frequency Flatness Adjustment 80 0 dB Range Flatness Adjustments 81 +10 dB Range Flatness Adjustments 83 +20 dB Range Flatness Adjustment 85 Pulse Width (Trailing Edge Delay) Adjustment 87 Pulse Edge Time Adjustment 88 Duty Cycle Adjustment 89 Output Amplifier Adjustment (Optional) 90 Calibration Errors 91

Contents

Chapter 5 Theory of Operation

Block Diagram 95 Main Power Supply 97 On-Board Power Supplies 98 Waveform DAC and Filters 100 Digital Waveform, Pulse, and Sync 101 Digital Waveform Translator 104 Amplitude Multiplier 106 Main Output Circuitry 107 System ADC 110 System DAC 112

Contents

Chapter 5 Theory of Operation (continued)

Synthesis IC 113 Timebase 115 Phase Locked Loops 116 Clock Divider 118 Trigger and Delay 120 Waveform RAM 122 Synchronous Multiplexer 123 Main Processor 124 Main Gate Array 125 DSP and Gateway 126 Earth-Referenced Logic 126 Front Panel 127

Chapter 6 Service

Operating Checklist 130 Types of Service Available 131 Repackaging for Shipment 132 Cleaning 132 Electrostatic Discharge (ESD) Precautions 133 Surface Mount Repair 133 Troubleshooting Hints 134 Self-Test Procedures 136 Disassembly 140

Contents

Chapter 7 Replaceable Parts

33250-66511 Main PC Assembly (A1) 153 33205-66502 Front-Panel PC Assembly (A2) 176 33250A Chassis Assembly 177 33250A Front-Panel Assembly 178 Manufacturer’s List 179

Chapter 8 Backdating 181

Contents

Chapter 9 Schematics

A1 Earth Referenced Communications Schematic 185 A1 Main Processor Schematic 186 A1 Main Gate Array Schematic 187 A1 Display Controller Schematic 188 A1 DSP Schematic 189 A1 Modulation Schematic 190 A1 System DAC Schematic 191 A1 Timebase Schematic 192 A1 Phase-Locked Loops Schematic 193 A1 Trigger Schematic 194 A1 Clock Divider and Control Schematic 195 A1 Synthesis IC Schematic 196 A1 Waveform Memory Schematic 197 A1 Synchronous Multiplexer Schematic 198 A1 Digital Waveform and Sync Schematic 199 A1 Variable-Edge Level Translation Schematic 200 A1 Waveform DAC, Filters, and Comparator Schematic 201 A1 Multiplier Schematic 202 A1 Main Output Circuitry Schematic 203 A1 Power Supply Schematic 204 A2 Keyboard Schematic 205 A2 Display Schematic 206 A1 Component Locator (top) 207 A1 Component Locator (bottom) 208 A2 Component Locator (top) 209 A2 Component Locator (bottom) 210

Specifications

Chapter 1 Specifications

Agilent 33250A Function / Arbitrary Waveform Generator

WAVEFORMS

Standard Waveforms: Sine, Square, Ramp,

Arbitrary Waveforms

Waveform Length: 1 to 64K points Amplitude Resolution: 12 bits (including sign) Repetition Rate: 1 µHz to 25 MHz Sample Rate: 200 MSa/s Filter Bandwidth: 50 MHz Non-Volatile Memory:

Pulse, Noise, Sin(x)/x, Exponential Rise, Exponential Fall, Negative Ramp, Cardiac, DC Volts

Four 64K waveforms

FREQUENCY CHARACTERISTICS

Sine: 1 µHz to 80 MHz Square: 1 µHz to 80 MHz Ramp: 1 µHz to 1 MHz Pulse: 500 µHz to 50 MHz Noise (Gaussian): 50 MHz bandwidth Arb: 1 µHz to 25 MHz

Resolution: 1 µHz;

Accuracy (1 year):

except pulse, 5 digits

2 ppm, 18°C to 28°C 3 ppm, 0°C to 55°C

SINEWAVE SPECTRAL PURITY

Harmonic Distortion

< 3 Vpp

DC to 1 MHz: 1 MHz to 5 MHz: 5 MHz to 80 MHz:

-60 dBc

-57 dBc

-37 dBc

> 3 Vpp

-55 dBc

-45 dBc

-30 dBc

SIGNAL CHARACTERISTICS

Square Wave

Rise / Fall Time: < 8 ns Overshoot: < 5% Asymmetry: 1% of period + 1 ns Jitter (rms)

< 2 MHz: 0.01% + 525 ps > 2 MHz: 0.1% + 75 ps

Duty Cycle

< 25 MHz: 20.0% to 80.0% 25 MHz to 50 MHz: 40.0% to 60.0% 50 MHz to 80 MHz: 50.0% (fixed)

Pulse

Period: 20.00 ns to 2000.0 s Pulse Width: 8.0 ns to 1999.9 s Variable Edge Time: 5.00 ns to 1.00 ms Overshoot: < 5% Jitter (rms): 100 ppm + 50 ps

Ramp

Linearity: < 0.1% of peak output Symmetry: 0.0% to 100.0%

Arb

Minimum Edge Time: < 10 ns Linearity: < 0.1% of peak output Settling Time: < 50 ns to 0.5% of

Jitter (rms): 30 ppm + 2.5 ns

final value

Total Harmonic Distortion

DC to 20 kHz: < 0.2% + 0.1 mVrms

Spurious (non-harmonic)

DC to 1 MHz: -60 dBc 1 MHz to 20 MHz: -50 dBc 20 MHz to 80 MHz: -50 dBc + 6 dBc/octave

Phase Noise (30 kHz band)

10 MHz < -65 dBc (typical) 80 MHz < -47 dBc (typical)

_______________

A total of four waveforms can be stored.

Harmonic distortion at low amplitudes is limited by a -70 dBm floor.

Spurious noise at low amplitudes is limited by a -75 dBm floor.

Edge time decreased at higher frequency.

Chapter 1 Specifications

Agilent 33250A Function /Arbitrary Waveform Generator

OUTPUT CHARACTERISTICS

Amplitude (into 50Ω): 10 mVpp to 10 Vpp

Accuracy (at 1 kHz, >10 mVpp, Autorange On):

± 1% of setting ±1 mVpp

Flatness (sinewave relative to 1 kHz, Autorange On)

< 10 MHz: ± 1% (0.1 dB) 10 MHz to 50 MHz: ± 2% (0.2 dB) 50 MHz to 80 MHz ± 5% (0.4 dB)

Units: Vpp, Vrms, dBm,

Resolution: 0.1 mV or 4 digits

Offset (into 50Ω): ± 5 Vpk ac + dc

Accuracy: 1% of setting + 2 mV

Waveform Output

Impedance: 50Ω typical (fixed)

Isolation: 42 Vpk max. to Earth Protection:

High Level, Low Level

+ 0.5% of amplitude

>10 MΩ (output disabled)

Short-circuit protected Overload relay automatically disables main output

MODULATION CHARACTERISTICS

AM Modulation

Carrier Waveforms: Modulating Waveforms:

Modulating Frequency: 2 mHz to 20 kHz Depth: 0.0% to 120.0% Source: Internal / External

Sine, Square, Ramp, Arb Sine, Square, Ramp, Noise, Arb

BURST

Waveforms:

Frequency: 1 µHz to 80 MHz Burst Count: 1 to 1,000,000 cycles,

Start / Stop Phase: -360 Internal Period: 1 ms to 500 s Gate Source: External Trigger Trigger Source: Single, External, or

Trigger Delay

N-Cycle, Infinite: 0.0 ns to 85.000 s

Sine, Square, Ramp, Pulse, Noise, Arb

or Infinite

.0° to

Internal Rate

SWEEP

Waveforms: Type: Linear or Logarithmic Direction: Up or Down Start F / Stop F: 100 µHz to 80 MHz

;

Sweep Time: 1 ms to 500 s Trigger: Single, External, or

Marker: Falling edge of Sync

Sine, Square, Ramp, Arb

Internal

signal (programmable)

+360.0

FM Modulation

Carrier Waveforms: Modulating Waveforms:

Modulating Frequency: 2 mHz to 20 kHz Peak Deviation: DC to 80 MHz Source: Internal / External

FSK

Carrier Waveforms: Modulating Waveforms: 50% duty cycle square Internal Rate: 2 mHz to 100 kHz Frequency Range: 1 µHz to 80 MHz Source: Internal / External

External Modulation Input

Voltage Range: ± 5V full scale Input Impedance: 10 kΩ Frequency: DC to 20 kHz

Sine, Square, Ramp, Arb Sine, Square, Ramp, Noise, Arb

Sine, Square, Ramp, Arb

_______________

Add 1/10th of output amplitude and offset specification per °C for operation outside of 18 °C to 28 °C range (1-year specification).

20 mVpp to 20 Vpp into open-circuit load.

dB rounded to 1 digit. Instrument adheres to “% ” specification.

Short-circuit protected to ground at all times.

Sine and square waveforms above 25 MHz are allowed only with an “Infinite” burst count.

Chapter 1 Specifications

Agilent 33250A Function / Arbitrary Waveform Generator

SYSTEM CHARACTERISTICS

Configuration TImes (typical)

Function Change

Standard: Pulse: 660 ms

Built-In Arb: Frequency Change: 24 ms Amplitude Change: 50 ms Offset Change: 50 ms Select User Arb: Modulation Change: < 200 ms

Arb Download Times GPIB / RS-232 (115 Kbps)

Arb Length Binary ASCII Integer ASCII Real

64K points 23 sec 92 sec 154 sec 16K points 6 sec 23 sec 39 sec

8K points 3 sec 12 sec 20 sec 4K points 1.5 sec 6 sec 10 sec 2K points 0.75 sec 3 sec 5 sec

102 ms

240 ms

< 400 ms for < 16K points

TRIGGER CHARACTERISTICS

Trigger Input

Input Level: TTL-compatible Slope: Rising or falling

Pulse Width: > 100 ns Input Impedance: 10 kΩ, DC coupled Latency

Sweep: < 10 µs (typical)

Burst: < 100 ns (typical) Jitter (rms)

Sweep: 2.5 µs

Burst: 1 ns;

Trigger Output

Level: Pulse Width: > 450 ns Maximum Rate: 1 MHz Fanout: < 4 Agilent 33250As

(selectable)

except pulse, 300 ps

TTL-compatible into 50

CLOCK REFERENCE

Phase Offset

Range: -360 Resolution: 0.001

External Reference Input

Lock Range: 10 MHz ± 35 kHz Level: 100 mVpp to 5 Vpp Impedance: Lock Time: < 2 s

Internal Reference Output

Frequency: 10 MHz

Level: 632 mVpp (0 dBm),

Impedance:

° to

1 kΩ nominal, ac coupled

nominal 50Ω nominal, ac coupled

SYNC OUTPUT

Level: TTL-compatible

Impedance: 50Ω nominal

_______________

Time to change parameter and output new signal.

Ω

Modulation or sweep off.

Times for 5-digit integer and 12-digit real numbers.

into > 1 kΩ

+360

Agilent 33250A Function /Arbitrary Waveform Generator

GENERAL SPECIFICATIONS

Power Supply: 100-240 V (±10%)

Power Consumption: 140 VA

Operating Environment:

Operating Altitude: 3000 meters

Pollution Degree: Indoor or Sheltered Use,

Storage Temperature:

Stored States: Four (4) named user

Power-On State: Default or Last

for 50-60 Hz operation, 100-127 V (±10%) for 50-400 Hz operation. IEC 60664 CAT II

0 °C to

°C

80% R.H. to 40 °C

IEC 60664 Degree 2

-30 °C to

configurations

Chapter 1 Specifications

Safety Designed to:

EMC Tested to:

Acoustic Noise: 40 dBA

Warm-Up Time: 1 hour

Calibration Interval: 1 year

Warranty: 3 years standard

Accessories Included:

IEC-61326-1

EN61010-1, CSA1010.1 UL-3111-1

IEC-61000-4-3 criteria B IEC-61000-4-6 criteria B

User’s Guide, Service Guide, Quick Reference Test Data, Connectivity Software, RS-232 Cable, Power Cord

Guide,

Interface: IEEE-488 and RS-232

standard

Language: SCPI-1997, IEEE-488.2

Dimensions (WxHxD)

Bench Top: 254 x 104 x 374 mm Rack Mount: 213 x 89 x 348 mm

Weight: 4.6 kg

_______________

Radiated and conducted immunity testing: When the product is tested at 3 V/m according to IEC/EN 61000-4-3:1995 or tested at 3 Vrms according to IEC/EN 61000-4-6:1996, the product may not meet criteria A, but does meet criteria B.

This ISM device complies with Canadian ICES-001.

Cet appareil ISM est conforme à la norme NMB-001 du Canada.

N10149

Chapter 1 Specifications

Agilent 33250A Function / Arbitrary Waveform Generator

PRODUCT DIMENSIONS

103.6 mm

254.4 mm

88.5 mm

216.6 mm 348.3 mm

374.0 mm

All dimensions are shown in millimeters.

Quick Start

One of the first things you will want to do with your function generator is to become acquainted with the front panel. We have written the exercises in this chapter to prepare the instrument for use and help you get familiar with some of its front-panel operations. This chapter is divided into the following sections:

• To Prepare the Function Generator for Use, on page 21

• To Adjust the Carrying Handle, on page 22

• To Set the Output Frequency, on page 23

• To Set the Output Amplitude, on page 24

• To Set a DC Offset Voltage, on page 26

• To Set the Duty Cycle, on page 27

• To Configure a Pulse Waveform, on page 28

• To View a Waveform Graph, on page 29

• To Output a Stored Arbitrary Waveform, on page 30

• To Use the Built-In Help System, on page 31

• To Rack Mount the Function Generator, on page 33

Chapter 2 Quick Start

Power Switch

To Prepare the Function Generator for Use

1 Check the list of supplied items.

Verify that you have received the following items with your instrument. If anything is missing, please contact your nearest Agilent Sales Office.

❑ One power cord.

❑ One User’s Guide.

❑ This Service Guide.

❑ One folded Quick Reference Guide.

❑ Certificate of Calibration.

❑ Connectivity software on CD-ROM.

❑ One RS-232 cable.

2 Connect the power cord and turn on the function generator.

Several power-on information messages are displayed after the function generator performs its power-on self-test. The GPIB address is displayed. The function generator powers up in the sine wave function at 1 kHz with an amplitude of 100 mV peak-to-peak (into a 50Ω termination). At power-on, the Output connector is disabled. To enable the Output connector, press the key.

If the function generator does not turn on, verify that the power cord is firmly connected to the power receptacle on the rear panel (the powerline voltage is automatically sensed at power-on). You should also make sure that the function generator is connected to a power source that is energized. Then, verify that the function generator is turned on.

If you need further assistance, refer to chapter 6 for instructions on returning the function generator to Agilent for service.

Chapter 2 Quick Start

To Adjust the Carrying Handle

To adjust the position, grasp the handle by the sides and pull outward. Then, rotate the handle to the desired position.

Bench-top viewing positions Carrying position

To Set the Output Frequency

Chapter 2 Quick Start

To Set the Output Frequency

At power-on, the function generator outputs a sine wave at 1 kHz with an amplitude of 100 mV peak-to-peak (into a 50Ω termination). The following steps show you how to change the frequency to 1.2 MHz.

1Press the “Freq” softkey.

The displayed frequency is either the power-on value or the frequency previously selected. When you change functions, the same frequency is used if the present value is valid for the new function. To set the waveform period instead, press the Freq softkey again to toggle to the Period softkey (the current selection is highlighted).

2 Enter the magnitude of the desired frequency.

Using the numeric keypad, enter the value “1.2”.

3 Select the desired units.

Press the softkey that corresponds to the desired units. When you select the units, the function generator outputs a waveform with the displayed frequency (if the output is enabled). For this example, press MHz

Note: You can also enter the desired value using the knob and arrow keys.

Chapter 2 Quick Start

To Set the Output Amplitude

At power-on, the function generator outputs a sine wave with an amplitude of 100 mV peak-to-peak (into a 50Ω termination).

The following steps show you how to change the amplitude to 50 mVrms.

1Press the “Ampl” softkey.

The displayed amplitude is either the power-on value or the amplitude previously selected. When you change functions, the same amplitude is used if the present value is valid for the new function. To set the amplitude using a high level and low level, press the Ampl softkey again to toggle to the HiLevel and LoLevel softkeys (the current selection is highlighted).

2 Enter the magnitude of the desired amplitude.

Using the numeric keypad, enter the value “50”.

3 Select the desired units.

Press the softkey that corresponds to the desired units. When you select the units, the function generator outputs the waveform with the displayed amplitude (if the output is enabled). For this example, press mV

Note: You can also enter the desired value using the knob and arrow keys.

RMS

Chapter 2 Quick Start

To Set the Output Amplitude

You can easily convert the displayed amplitude from one unit to another. For example, the following steps show you how to convert the amplitude from Vrms to Vpp.

4 Enter the numeric entry mode.

Press the key to enter the numeric entry mode.

5 Select the new units.

Press the softkey that corresponds to the desired units. The displayed value is converted to the new units. For this example, press the Vpp softkey to convert 50 mVrms to its equivalent in volts peak-to-peak.

To change the displayed amplitude by decades, press the right-arrow key to move the cursor to the units on the right side of the display. Then, rotate the knob to increase or decrease the displayed amplitude by decades.

Chapter 2 Quick Start

To Set a DC Offset Voltage

At power-on, the function generator outputs a sine wave with a dc offset of 0 volts (into a 50Ω termination). The following steps show you how to

change the offset to –1.5 mVdc.

1Press the “Offset” softkey.

The displayed offset voltage is either the power-on value or the offset previously selected. When you change functions, the same offset is used if the present value is valid for the new function.

2 Enter the magnitude of the desired offset.

Using the numeric keypad, enter the value “–1.5”.

3 Select the desired units.

Press the softkey that corresponds to the desired units. When you select the units, the function generator outputs the waveform with the displayed offset (if the output is enabled). For this example, press mVdc.

Note: You can also enter the desired value using the knob and arrow keys.

Note: To select dc volts from the front panel, press and then select

the DC On softkey. Press the Offset softkey to enter the desired voltage level.

To Set the Duty Cycle

Chapter 2 Quick Start

To Set the Duty Cycle

Applies only to square waves. At power-on, the duty cycle for square waves if 50%. You can adjust the duty cycle from 20% to 80% for output frequencies up to 25 MHz. The following steps show you how to change

the duty cycle to 30%.

1 Select the square wave function.

Press the key and then set the desired output frequency to any value less than 25 MHz.

2Press the “Duty Cycle” softkey.

The displayed duty cycle is either the power-on value or the percentage previously selected. The duty cycle represents the amount of time per cycle that the square wave is at a high level (note the icon on the right side of the display).

3 Enter the desired duty cycle.

Using the numeric keypad or the knob, select a duty cycle value of “30”. The function generator adjusts the duty cycle immediately and outputs a square wave with the specified value (if the output is enabled).

Chapter 2 Quick Start

To Configure a Pulse Waveform

You can configure the function generator to output a pulse waveform with variable pulse width and edge time. The following steps show you

how to configure a 500 ms pulse waveform with a pulse width of 10 ms and edge times of 50 µs.

1 Select the pulse function.

Press the key to select the pulse function and output a pulse waveform with the default parameters.

2 Set the pulse period.

Press the Period softkey and then set the pulse period to 500 ms.

3 Set the pulse width.

Press the Pulse Width softkey and then set the pulse width to 10 ms. The pulse width represents the time from the 50% threshold of the rising edge to the 50% threshold of the next falling edge (note the display icon).

4 Set the edge time for both edges.

Press the Edge Time softkey and then set the edge time for both the rising and falling edges to 50 µs. The edge time represents the time from the 10% threshold to the 90% threshold of each edge (note the display icon).

To View a Waveform Graph

Chapter 2 Quick Start

To View a Waveform Graph

In the Graph Mode, you can view a graphical representation of the current waveform parameters. Each softkey parameter is shown in a different color corresponding to the lines above the softkeys at the bottom of the display. Note that the softkeys are listed in the same order as in the normal display mode.

1 Enable the Graph Mode.

Press the key to enable the Graph Mode. The name of the parameter currently selected is shown in the upper-left corner of the display and the

numeric value is highlighted.

2 Select the desired parameter.

To select a specific parameter, note the colored bars above the softkeys at the bottom of the display and select the corresponding color. For example, to select amplitude, press the softkey below the magenta-colored bar.

• As in the normal display mode, you can edit numbers using the numeric keypad or the knob and arrow keys.

• Parameters which normally toggle when you press a key a second time (e.g., Freq / Period) also toggle in the Graph Mode.

• To exit the Graph Mode, press again.

The key also serves as a key to restore front-panel control after remote interface operations.

Chapter 2 Quick Start

To Output a Stored Arbitrary Waveform

There are five built-in arbitrary waveforms stored in non-volatile memory.

The following steps show you how to output the built-in “exponential fall” waveform from the front panel.

1 Select the arbitrary waveform function.

When you press the key to select the arbitrary waveform function, a temporary message is displayed indicating which waveform is currently selected (the default is “exponential rise”).

2 Select the active waveform.

Press the Select Wform softkey and then press the Built-In softkey to select from the five built-in waveforms. Then press the Exp Fall softkey. The waveform is output using the present settings for frequency, amplitude, and offset unless you change them.

The selected waveform is now assigned to the key. Whenever you press this key, the selected arbitrary waveform is output. To quickly determine which arbitrary waveform is currently selected, press .

To Use the Built-In Help System

Chapter 2 Quick Start

The built-in help system is designed to provide context-sensitive assistance on any front-panel key or menu softkey. A list of help topics is also available to assist you with several front-panel operations.

1 View the help information for a function key.

Press and hold down the key. If the message contains more information than will fit on the display, press the ↓ softkey or turn the knob clockwise to view the remaining information.

Press DONE to exit the help menu.

2 View the help information for a menu softkey.

Press and hold down the Freq softkey. If the message contains more information than will fit on the display, press the ↓ softkey or rotate the knob clockwise to view the remaining information.

Press DONE to exit the help menu.

Chapter 2 Quick Start

To Use the Built-In Help System

3 View the list of help topics.

Press the key to view the list of available help topics. To scroll through the list, press the ↑ or ↓ softkey or rotate the knob. Select the third topic “Get HELP on any key” and then press SELECT.

Press DONE to exit the help menu.

4 View the help information for displayed messages.

Whenever a limit is exceeded or any other invalid configuration is found, the function generator will display a message. For example, if you enter a value that exceeds the frequency limit for the selected function, a message will be displayed. The built-in help system provides additional information on the most recent message to be displayed.

Press the key, select the first topic “View the last message displayed”, and then press SELECT.

Local Language Help: The built-in help system in available in multiple languages. All messages, context-sensitive help, and help topics appear in the selected language. The menu softkey labels and status line messages are not translated.

To select the local language, press the key, press the System softkey, and then press the Help In softkey. Select the desired language.

Chapter 2 Quick Start

To Rack Mount the Function Generator

You can mount the Agilent 33250A in a standard 19-inch rack cabinet using one of two optional kits available. Instructions and mounting hardware are included with each rack-mounting kit. Any Agilent System II instrument of the same size can be rack-mounted beside the Agilent 33250A.

Note: Remove the carrying handle, and the front and rear rubber bumpers, before rack-mounting the instrument.

To remove the handle, rotate it to vertical and pull the ends outward.

Front Rear (bottom view)

To remove the rubber bumper, stretch a corner and then slide it off.

Chapter 2 Quick Start

To Rack Mount the Function Generator

To rack mount a single instrument, order adapter kit 5063-9240.

To rack mount two instruments side-by-side, order lock-link kit 5061-9694 and flange kit 5063-9212. Be sure to use the support rails in the rack cabinet.

In order to prevent overheating, do not block the flow of air into or out of the instrument. Be sure to allow enough clearance at the rear, sides, and bottom of the instrument to permit adequate internal airflow.

Front-Panel Menu Operation

This chapter introduces you to the front-panel keys and menu operation. This chapter does not give a detailed description of every front-panel key or menu operation. It does, however, give you an overview of the frontpanel menus and many front-panel operations. See the Agilent 33250A User’s Guide for a complete discussion of the function generator’s capabilities and operation.

• Front-Panel Menu Reference, on page 37

• To Reset the Function Generator, on page 39

• To Select the Output Termination, on page 39

• To Read the Calibration Information, on page 40

• To Unsecure and Secure for Calibration, on page 41

• To Store the Instrument State, on page 44

• To Configure the Remote Interface, on page 45

Chapter 3 Front-Panel Menu Operation

Front-Panel Menu Reference

This section gives an overview of the front-panel menus. The remainder of this chapter shows examples of using the front-panel menus.

Configure the modulation parameters for AM, FM, and FSK.

• Select the modulation type.

• Select an internal or external modulation source.

• Specify the AM modulation depth, modulating frequency, and modulation shape. Specify the FM frequency deviation, modulating frequency, and modulation shape.

•

• Specify the FSK “hop” frequency and FSK rate.

Configure the parameters for frequency sweep.

• Select linear or logarithmic sweeping.

• Select the start/stop frequencies or

• Select the time in seconds required to complete a sweep.

• Specify a marker frequency.

• Specify an internal or external trigger source for the sweep.

• Specify the slope (rising or falling edge) for an external trigger source.

• Specify the slope (rising or falling edge) of the “Trig Out” signal.

Configure the parameters for burst.

• Select the triggered (N Cycle) or externally-gated burst mode.

• Select the number of cycles per burst (1 to 1,000,000, or Infinite).

• Select the starting phase angle of the burst (-360° to +360°).

• Specify the time from the start of one burst to the start of the next burst.

• Specify a delay between the trigger and the start of the burst.

• Specify an internal or external trigger source for the burst.

• Specify the slope (rising or falling edge) for an external trigger source.

• Specify the slope (rising or falling edge) of the “Trig Out” signal.

center/ span frequencies.

Chapter 3 Front-Panel Menu Operation

Front-Panel Menu Reference

Store and recall instrument states.

• Store up to four instrument states in non-volatile memory.

• Assign a custom name to each storage location.

• Recall stored instrument states.

• Restore all instrument settings to their factory default values.

• Select the instrument’s power-on configuration (last or factory default).

Configure system-related parameters.

• Generate a dc-only voltage level.

• Enable/disable the Sync signal which is output from the “Sync” connector.

• Select the output termination (1Ω to 10 kΩ, or Infinite).

• Enable/disable amplitude autoranging.

• Select the waveform polarity (normal or inverted).

• Select the GPIB address.

• Configure the RS-232 interface (baud rate, parity, and handshake mode). Select how periods and commas are used in numbers displayed on the front panel.

•

• Select the local language for front-panel messages and help text.

• Enable/disable the tone heard when an error is generated.

• Enable/disable the display bulb-saver mode.

• Adjust the contrast setting of the front-panel display.

• Perform an instrument self-test.

• Secure/unsecure the instrument for calibration and perform manual calibrations.

• Query the instrument’s firmware revision codes.

View the list of Help topics.

• View the last message displayed.

• View the remote command error queue.

• Get HELP on any key.

• How to generate a dc-only voltage level.

• How to generate a modulated waveform.

• How to create an arbitrary waveform.

• How to reset the instrument to its default state.

• How to view a waveform in the Graph Mode.

• How to synchronize multiple instruments.

• How to obtain Agilent Technical Support.

Chapter 3 Front-Panel Menu Operation

To Reset the Function Generator

To reset the instrument to its factory default state, press and then select the Set to Defaults softkey. Select YES to confirm the operation.

A complete listing of the instrument’s power-on and reset conditions, see the “Factory Default Settings” table inside the rear cover of this manual.

To Select the Output Termination

The Agilent 33250A has a fixed series output impedance of 50 ohms to the front-panel Output connector. If the actual load impedance is different than the value specified, the displayed amplitude and offset levels will be incorrect. The load impedance setting is simply provided as a convenience to ensure that the displayed voltage matches the expected load.

1Press .

2 Navigate the menu to set the output termination.

Press the Output Setup softkey and then select the Load softkey.

3 Select the desired output termination.

Use the knob or numeric keypad to select the desired load impedance or press the Load softkey again to choose “High Z”.

Chapter 3 Front-Panel Menu Operation

To Read the Calibration Information

You can use the instrument’s calibration memory to read the calibration count and calibration message.

Calibration Count You can query the instrument to determine how many calibrations have been performed. Note that your instrument was calibrated before it left the factory. When you receive your instrument, read the count to determine its initial value. The count value increments by one for each calibration point, and a complete calibration may increase the value by many counts.

Calibration Message The instrument allows you to store one message in calibration memory. For example, you can store such information as the date when the last calibration was performed, the date when the next calibration is due, the instrument’s serial number, or even the name and phone number of the person to contact for a new calibration.

You can record a calibration message only from the remote interface and only when the instrument is unsecured.

You can read the message from either the front-panel or over the remote interface. You can read the calibration message whether the instrument is secured or unsecured.

1 Select the Cal Info interface.

Press and then select the Cal Info softkey from the “Test/Cal” menu.

The first line in the display shows the calibration count. The second line shows the calibration message. The last line indicates the current version of the firmware.

The calibration information will time-out and disappear after a few seconds. Select the Cal Info softkey to show the information again.

2 Exit the menu.

Press the DONE softkey.

Chapter 3 Front-Panel Menu Operation

To Unsecure and Secure for Calibration

This feature allows you to enter a security code to prevent accidental or unauthorized adjustments of the instrument. When you first receive your instrument, it is secured. Before you can adjust the instrument, you must unsecure it by entering the correct security code.

• The security code is set to AT33250A when the instrument is shipped from the factory. The security code is stored in non-volatile memory, and does not change when power has been off, after a Factory Reset (*RST command), or after an Instrument Preset (SYSTem:PRESet command).

• The security code may contain up to 12 alphanumeric characters. The first character must be a letter, but the remaining characters can be letters, numbers, or an underscore ( _ ). You do not have to use all 12 characters but the first character must always be a letter.

Note: If you forget your security code, you can disable the security feature by applying a temporary short inside the instrument as described in “To Unsecure the Instrument Without the Security Code”, on page 69.

Chapter 3 Front-Panel Menu Operation

To Unsecure and Secure for Calibration

To Unsecure for Calibration

1 Select the Secure Code interface.

Press and then select the Test/C a l softkey.

2 Enter the Secure Code.

Use the knob to change the displayed character. Use the arrow keys to move to the next character.

When the last character of the secure code is entered, the instrument will be unsecured.

3 Exit the menu.

Press the DONE softkey.

Chapter 3 Front-Panel Menu Operation

To Unsecure and Secure for Calibration

To Secure After Calibration

1 Select the Secure Code interface.

Press and then select the Test/C a l softkey.

2Enter a Secure Code.

Enter up to 12 alphanumeric characters. The first character must be a letter.

Use the knob to change the displayed character. Use the arrow keys to move to the next character.

3 Secure the Instrument.

Select the Secure softkey.

4 Exit the menu.

Press the DONE softkey.

Chapter 3 Front-Panel Menu Operation

To Store the Instrument State

You can store the instrument state in one of four non-volatile storage locations. A fifth storage location automatically holds the power-down configuration of the instrument. When power is restored, the instrument can automatically return to its state before power-down.

1 Select the desired storage location.

Press and then select the Store State softkey.

2 Select a custom name for the selected location.

If desired, you can assign a custom name to each of the four locations.

• The name can contain up to 12 characters. The first character must be a letter but the remaining characters can be letters, numbers, or the underscore character (“_”).

• To add additional characters, press the right-arrow key until the cursor is to the right of the existing name and then turn the knob.

• To delete all characters to the right of the cursor position, press .

• To use numbers in the name, you can enter them directly from the numeric keypad. Use the decimal point from the numeric keypad to add the underscore character (“_” ) to the name.

3 Store the instrument state.

Press the STORE STATE softkey. The instrument stores the selected function, frequency, amplitude, dc offset, duty cycle, symmetry, as well as any modulation parameters in use. The instrument does not store volatile waveforms created in the arbitrary waveform function.

Chapter 3 Front-Panel Menu Operation

To Configure the Remote Interface

The instrument is shipped with both a GPIB (IEEE-488) interface and an RS-232 interface. Only one interface can be enabled at a time. The GPIB interface is selected when the instrument is shipped from the factory.

GPIB Configuration

1 Select the GPIB interface.

Press and then select the GPIB softkey from the “I/O” menu.

2 Select the GPIB address.

Press the GPIB Address softkey and enter the desired address using the numeric keypad or knob. The factory setting is “10”.

The GPIB address is shown on the front-panel display at power-on.

3 Exit the menu.

Press the DONE softkey.

Chapter 3 Front-Panel Menu Operation

To Configure the Remote Interface

RS-232 Configuration

1 Select the RS-232 interface.

Press and then select the RS-232 softkey from the “I/O” menu.

2 Set the baud rate.

Press the Baud Rate softkey and select one of the following: 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600 (factory setting), or 115200 baud.

3 Select the parity and number of data bits.

Press the Parity / # Bits softkey and select one of the following: None (8 data bits, factory setting), Even (7 data bits), or Odd (7 data bits). When you set the parity, you are also setting the number of data bits.

4 Select the handshake mode.

Press the Handshake softkey and select one of the following: None, DTR /DSR (factory setting), Modem, RTS / CTS, or XON / XOFF.

5 Exit the menu.

Press the DONE softkey.

Calibration Procedures

This chapter contains procedures for verification of the instrument’s performance and adjustment (calibration). The chapter is divided into the following sections:

• Agilent Technologies Calibration Services, on page 49

• Calibration Interval, on page 50

• Adjustment is Recommended, on page 50

• Time Required for Calibration, on page 51

• Automating Calibration Procedures, on page 52

• Recommended Test Equipment, on page 53

• Test Considerations, on page 54

• Performance Verification Tests, on page 55

• Internal Timebase Verification, on page 60

• AC Amplitude (high-impedance) Verification, on page 61

• Low Frequency Flatness Verification, on page 62

• 0 dB Range Flatness Verification, on page 63

• +10 dB Range Flatness Verification, on page 65

• +20 dB Range Flatness Verification, on page 66

• Calibration Security, on page 68

• Calibration Message, on page 70

• Calibration Count, on page 70

• General Calibration/Adjustment Procedure, on page 71

• Sequence of Adjustments, on page 72

• Aborting a Calibration in Progress, on page 72

• Self-Test, on page 73

• Frequency (Internal Timebase) Adjustment, on page 74

• Internal ADC Adjustment, on page 75

• Output Impedance Adjustment, on page 76

• AC Amplitude (high-impedance) Adjustment, on page 78

• Low Frequency Flatness Adjustment, on page 80

• 0 dB Range Flatness Adjustments, on page 81

• +10 dB Range Flatness Adjustments, on page 83

• +20 dB Range Flatness Adjustment, on page 85

• Pulse Width (Trailing Edge Delay) Adjustment, on page 87

• Pulse Edge Time Adjustment, on page 88

• Duty Cycle Adjustment, on page 89

• Output Amplifier Adjustment (Optional), on page 90

• Calibration Errors, on page 91

Chapter 4 Calibration Procedures

Agilent Technologies Calibration Services

Closed-Case Electronic Calibration The instrument features closedcase electronic calibration. No internal mechanical adjustments are required. The instrument calculates correction factors based upon the input reference value you set. The new correction factors are stored in non-volatile memory until the next calibration adjustment is performed. Non-volatile EEPROM calibration memory does not change when power has been off or after a remote interface reset.

Agilent Technologies Calibration Services

When your instrument is due for calibration, contact your local Agilent Technologies Service Center for a low-cost recalibration. The Agilent 33250A is supported on automated calibration systems which allow Agilent to provide this service at competitive prices.

Chapter 4 Calibration Procedures

Calibration Interval

The instrument should be calibrated on a regular interval determined by the measurement accuracy requirements of your application. A 1-year interval is adequate for most applications. Accuracy specifications are warranted only if adjustment is made at regular calibration intervals. Accuracy specifications are not warranted beyond the 1-year calibration interval. Agilent Technologies does not recommend extending calibration intervals beyond 2 years for any application.

Adjustment is Recommended

Whatever calibration interval you select, Agilent Technologies recommends that complete re-adjustment should always be performed at the calibration interval. This will assure that the Agilent 33250A will remain within specification for the next calibration interval. This criteria for re-adjustment provides the best long-term stability. Performance data measured using this method can be used to extend future calibration intervals.

Use the Calibration Count (see page 70) to verify that all adjustments have been performed.

Chapter 4 Calibration Procedures

Time Required for Calibration

The Agilent 33250A can be automatically calibrated under computer control. With computer control you can perform the complete calibration procedure and performance verification tests in approximately 30 minutes once the instrument is warmed-up (see “Test Considerations” on page 54). Manual adjustments and verifications, using the recommended test equipment, will take approximately 2 hours.

START

Incoming

Verification?

Perform

Adjustments

(approx 1 Hour)

Do Performance Verification Tests

(approx 1 Hour)

DONE

YES

Do Performance Verification Tests

(approx 1 Hour)

Chapter 4 Calibration Procedures

Automating Calibration Procedures

You can automate the complete verification and adjustment procedures outlined in this chapter if you have access to programmable test equipment. You can program the instrument configurations specified for each test over the remote interface. You can then enter readback verification data into a test program and compare the results to the appropriate test limit values.

You can also adjust the instrument from the remote interface. Remote adjustment is similar to the local front-panel procedure. You can use a computer to perform the adjustment by first selecting the required function and range. The calibration value is sent to the instrument and then the calibration is initiated over the remote interface. The instrument must be unsecured prior to initiating the calibration procedure.

For further information on programming the instrument, see chapters 3 and 4 in the Agilent 33250A User’s Guide.

Chapter 4 Calibration Procedures

Recommended Test Equipment

The test equipment recommended for the performance verification and adjustment procedures is listed below. If the exact instrument is not available, substitute calibration standards of equivalent accuracy.

Instrument Requirements Recommended Model Use*

Digital Multimeter (DMM)

Power Meter 100 kHz to 100 MHz

ac volts, true rms, ac coupled

accuracy: ±0.02% to 1 MHz

dc volts

accuracy: 50 ppm resolution: 100 µV

Resistance

Offset-compensated accuracy: ±0.1Ω

1 µW to 100 mW (–30 dBm to +20 dBm) accuracy: 0.02 dB resolution: 0.01 dB

Agilent 3458A Q, P, T

Agilent E4418B Q, P, T

Power Head 100 kHz to 100 MHz

1 µW to 100 mW (–30 dBm to +20 dBm)

Attenuator –20 dB Agilent 8491A Opt 020 Q, P, T

Frequency Meter accuracy: 0.1 ppm Agilent 53131A Opt 010

Oscilloscope 500 MHz

2 Gs/second 50Ω input termination

Adapter N type (m) to BNC (m) N type (m) to BNC (m) Q, P, T

Cable BNC (m) to dual-banana (f) Agilent 10110B Q, P, T

Cable (2 required) Dual banana (m) to dual banana (m) Agilent 11000-60001 Q, P, T

Cable RG58, BNC (m) to dual banana Agilent 11001-60001 Q, P, T

Cable RG58, BNC (m) to BNC (m) Agilent 8120-1840 Q, P, T

* Q = Quick Verification P = Performance Verification

T = Troubleshooting O = Optional Verification

Agilent 8482A Q, P, T

Q, P, T

(high stability)

Agilent 54831B Q, P, T

Chapter 4 Calibration Procedures

Test Considerations

For optimum performance, all procedures should comply with the following recommendations:

• Assure that the calibration ambient temperature is stable and between 18 °C and 28 °C. Ideally, the calibration should be performed at 23 °C

• Assure ambient relative humidity is less than 80%.

• Allow a 1-hour warm-up period before verification or adjustment.

• Keep the measurement cables as short as possible, consistent with the impedance requirements.

• Use only RG-58 or equivalent 50

±1 °C.

Ω cable.

Chapter 4 Calibration Procedures

Performance Verification Tests

Use the Performance Verification Tests to verify the measurement performance of the instrument. The performance verification tests use the instrument’s specifications listed in the “Specifications” chapter beginning on page 13.

You can perform four different levels of performance verification tests:

• Self-Test A series of internal verification tests that give high

confidence that the instrument is operational.

• Quick Verification A combination of the internal self-tests and

selected verification tests.

• Performance Verification Tests An extensive set of tests that are

recommended as an acceptance test when you first receive the instrument or after performing adjustments.

• Optional Verification Tests Tests not performed with every

calibration. Perform these tests following repairs to the output amplifier.

Chapter 4 Calibration Procedures

Performance Verification Tests

Self-Test

A brief power-on self-test occurs automatically whenever you turn on the instrument. This limited test assures that the instrument is operational.

To perform a complete self-test:

1 Press on the front panel.

2 Select the Self Test softkey from the “Test/Cal” menu.

A complete description of the self-tests can be found in chapter 6. The instrument will automatically perform the complete self-test procedure when you release the key. The self-test will complete in approximately 30 seconds.

• If the self-test is successful, “Self Test Pass” is displayed on the front panel.

• If the self-test fails, “Self Test Fail” and an error number are displayed. If repair is required, see chapter 6, “Service,” for further details.

Chapter 4 Calibration Procedures

Performance Verification Tests

Quick Performance Check

The quick performance check is a combination of internal self-test and an abbreviated performance test (specified by the letter performance verification tests). This test provides a simple method to achieve high confidence in the instrument’s ability to functionally operate and meet specifications. These tests represent the absolute minimum set of performance checks recommended following any service activity. Auditing the instrument’s performance for the quick check points (designated by a Q) verifies performance for normal accuracy drift mechanisms. This test does not check for abnormal component failures.

To perform the quick performance check, do the following:

1 Perform a complete self-test. A procedure is given on page 56.

Q in the

2 Perform only the performance verification tests indicated with the

letter Q.

3 If the instrument fails the quick performance check, adjustment or

repair is required.

Performance Verification Tests

The performance verification tests are recommended as acceptance tests when you first receive the instrument. The acceptance test results should be compared against the specifications given in chapter 1. After acceptance, you should repeat the performance verification tests at every calibration interval.

If the instrument fails performance verification, adjustment or repair is required.

Adjustment is recommended at every calibration interval. If adjustment is not made, you must guard band, using no more than 80% of the specifications listed in chapter 1, as the verification limits.

Chapter 4 Calibration Procedures

Performance Verification Tests

Amplitude and Flatness Verification Procedures

Special Note: Measurements made during the AC Amplitude (highimpedance) Verification procedure (see page 61) are used as reference measurements in the flatness verification procedures (beginning on page 62). Additional reference measurements and calculated references are used in the flatness verification procedures. Photo-copy and use the table on page 59 to record these reference measurements and perform the calculations.

The flatness verification procedures use both a DMM and a Power Meter to make the measurements. To correct the difference between the DMM and Power Meter measurements, the Power Meter reference measurement level is adjusted to set the 0.00 dB level to the DMM measurement made at 1 kHz. The flatness error of the DMM at 100 kHz is used to set the required 0.00 dB reference.

The instrument internally corrects the difference between the high-Z input of the DMM and the 50Ω input of the Power Meter when setting the output level.

The reference measurements must also be converted from Vrms (made by the DMM) to dBm (made by the Power Meter).

The equation used for the conversion from Vrms (High-Z) to dBm (at 50Ω) is as follows:

Power (dBm) = 10 log(5.0 * V

Flatness measurements for the –10 dB, –20dB, and –30 dB attenuator ranges are verified as a part of the 0 dB verification procedure. No separate verification procedure is given for these ranges.

rms

)

Chapter 4 Calibration Procedures

Performance Verification Tests

Amplitude and Flatness Verification Worksheet

1. Enter the following measurements (from procedure on page 61).

1kHz_0dB_reference = __________________________ Vrms

1kHz_10dB_reference = __________________________ Vrms

1kHz_20dB_reference = __________________________ Vrms

2. Calculate the dBm value of the rms voltages.

1kHz_0dB_reference_dBm ==10 * log(5.0 * 1kHz_0dB_reference2)

__________________________ dBm

1kHz_10dB_reference_dBm ==10 * log(5.0 * 1kHz_10dB_reference

__________________________ dBm

1kHz_20dB_reference_dBm ==10 * log(5.0 * 1kHz_20dB_reference

__________________________ dBm

)

3. Enter the following measurements (from the procedure on page 62).

100kHz_0dB_reference = __________________________ Vrms

100kHz_10dB_reference = __________________________ Vrms

100kHz_20dB_reference = __________________________ Vrms

4. Calculate the dBm value of the rms voltages.

100kHz_0dB_reference_dBm ==10 * log(5.0 * 100kHz_0dB_reference2)

__________________________ dBm

100kHz_10dB_reference_dBm ==10 * log(5.0 * 100kHz_10dB_reference

__________________________ dBm

100kHz_20dB_reference_dBm ==10 * log(5.0 * 100kHz_20dB_reference

__________________________ dBm

)

5. Calculate the offset values.

100kHz_0dB_offset ==100kHz_0dB_reference_dBm – 1kHz_0dB_reference_dBm

__________________________ dBm (use on page 63)

100kHz_10dB_offset ==100kHz_10dB_reference_dBm

__________________________ dBm (use on page 65)

100kHz_20dB_offset ==100kHz_20dB_reference_dBm – 1kHz_20dB_reference_dBm

__________________________ dBm (use on page 66)

– 1kHz_10dB_reference_dBm

Chapter 4 Calibration Procedures

Internal Timebase Verification

This test verifies the output frequency accuracy of the instrument. All output frequencies are derived from a single generated frequency.

1 Connect a frequency counter as shown below (the frequency counter

input should be terminated at 50

Ω).

2 Set the instrument to the output described in the table below and

measure the output frequency. Be sure the instrument output is enabled.

Agilent 33250A Measurement

Function Amplitude Frequency Nominal Error

Q Sine Wave 1.00 Vpp 10.000,000,0 MHz 10.000 MHz ±20 Hz

3 Compare the measured frequency to the test limits shown in the table.

Chapter 4 Calibration Procedures

AC Amplitude (high-impedance) Verification

This procedure checks the ac amplitude output accuracy at a frequency of 1 kHz, and establishes reference measurements for the higher frequency flatness verification procedures.

1 Set the DMM to measure Vrms Volts. Connect the DMM as shown below.

2 Set the instrument to each output described in the table below and

measure the output voltage with the DMM. Press to set the output impedance to High-Z. Be sure the output is enabled.

Agilent 33250A Measurement

Output Setup Function Frequency Amplitude Nominal Error*

Q High Z Sine Wave 1.000 kHz 20.0 mVrms 0.020 Vrms ± 0.00091 Vrms

Q High Z Sine Wave 1.000 kHz 67.0 mVrms 0.067 Vrms ± 0.00138 Vrms

Q High Z Sine Wave 1.000 kHz 200.0 mVrms 0.200 Vrms ± 0.00271 Vrms

Q High Z Sine Wave 1.000 kHz 670.0 mVrms 0.670 Vrms

Q High Z Sine Wave 1.000 kHz 2.000 Vrms 2.0000 Vrms 2± 0.0207 Vrms

Q High Z Sine Wave 1.000 kHz 7.000 Vrms 7.000 Vrms

Q High Z Square Wave

* Based upon 1% of setting ±1 mVpp (50Ω); converted to Vrms for High-Z.

Enter the measured value on the worksheet (page 59) as 1kHz_0dB_reference.

Enter the measured value on the worksheet (page 59) as 1kHz_10dB_reference.

Enter the measured value on the worksheet (page 59) as 1kHz_20dB_reference.

Square wave amplitude accuracy is not specified. This measurement and error

may be used as a guideline for typical operation.

1.000 kHz 900.0 mVrms 0.900 Vrms ± 0.0100 Vrms

± 0.00741 Vrms

± 0.0707 Vrms

3 Compare the measured voltage to the test limits shown in the table.

Chapter 4 Calibration Procedures

Low Frequency Flatness Verification

This procedure checks the AC amplitude flatness at 100 kHz using the reference measurements recorded in the Amplitude and Flatness Verification Worksheet. These measurements also establish an error value used to set the power meter reference. The transfer measurements are made at a frequency of 100 kHz using both the DMM and the power meter.

1 Set the DMM to measure ac Volts. Connect the DMM as shown in the

figure on page 61.

2 Set the instrument to each output described in the table below and

measure the output voltage with the DMM. Press to set the output

impedance to High-Z. Be sure the output is enabled.

Agilent 33250A Measurement

Output Setup Function Frequency Amplitude Nominal Error

Q High Z Sine Wave 100.000 kHz 670.0 mVrms 0.670 Vrms

Q High Z Sine Wave 100.000 kHz 2.0 Vrms 2.000 Vrms

Q High Z Sine Wave 100.000 kHz 7.000 Vrms 7.000 Vrms

Enter the measured value on the worksheet (page 59)

as 100kHz_0dB_reference.

Enter the measured value on the worksheet (page 59)

as 100kHz_10dB_reference.

Enter the measured value on the worksheet (page 59)

as 100kHz_20dB_reference.

± 0.0067 Vrms

± 0.020 Vrms

± 0.070 Vrms

3 Compare the measured voltage to the test limits shown in the table.

4 You have now recorded all the required measurements on the worksheet

(page 59). Complete the worksheet by making all the indicated calculations.

Chapter 4 Calibration Procedures

0 dB Range Flatness Verification

This procedure checks the high frequency ac amplitude flatness above 100 kHz on the 0 dB attenuator range.

1 Connect the power meter to measure the output amplitude of the

instrument as shown below.

2 Set the power meter reference level to equal 100kHz_0dB_offset.

This sets the power meter to directly read the flatness error specification. 100kHz_0dB_offset is calculated on the Amplitude and Flatness Verification Worksheet.

Chapter 4 Calibration Procedures

0 dB Range Flatness Verification

3 Set the instrument to each output described in the table below and

measure the output amplitude with the power meter. Press to set the output impedance to 50Ω. Be sure the output is enabled.

Agilent 33250A Measurement

Output Setup Function Amplitude Frequency Nominal Error

Q 50 Ω Sine Wave +3.51 dBm 100.000 kHz 0 dB ± 0.086 dB

50 Ω Sine Wave +3.51 dBm 200.000 kHz 0 dB ± 0.086 dB

50 Ω Sine Wave +3.51 dBm 500.000 kHz 0 dB ± 0.086 dB

50 Ω Sine Wave +3.51 dBm 1.500 MHz 0 dB ± 0.086 dB

50 Ω Sine Wave +3.51 dBm 5.000 MHz 0 dB ± 0.086 dB

Q 50 Ω Sine Wave +3.51 dBm 10.000 MHz 0 dB ± 0.086 dB

50 Ω Sine Wave +3.51 dBm 25.000 MHz 0 dB ± 0.177 dB

50 Ω Sine Wave +3.51 dBm 40.000 MHz 0 dB ± 0.177 dB

Q 50 Ω Sine Wave +3.51 dBm 50.000 MHz 0 dB ± 0.177 dB

50 Ω Sine Wave +3.51 dBm 60.000 MHz 0 dB ± 0.423 dB

50 Ω Sine Wave +3.51 dBm 65.000 MHz 0 dB ± 0.423 dB

50 Ω Sine Wave +3.51 dBm 70.000 MHz 0 dB ± 0.423 dB

50 Ω Sine Wave +3.51 dBm 75.000 MHz 0 dB ± 0.423 dB

Q 50 Ω Sine Wave +3.51 dBm 80.000 MHz 0 dB ± 0.423 dB

4 Compare the measured output to the test limits shown in the table.

Chapter 4 Calibration Procedures

+10 dB Range Flatness Verification

This procedure checks the high frequency ac amplitude flatness above 100 kHz on the +10 dB attenuator range.

1 Connect the power meter to measure the output amplitude of the

instrument as shown on page 63.

2 Set the power meter reference level to equal to the calculated

100kHz_10dB_offset value. This sets the power meter to directly read the flatness error specification. 100kHz_10dB_offset is calculated on the Amplitude and Flatness Verification Worksheet.

3 Set the instrument to each output described in the table below and

measure the output amplitude with the power meter. Press to set

the output impedance to 50Ω. Be sure the output is enabled.

Agilent 33250A Measurement

Output Setup Function Amplitude Frequency Nominal Error

Q 50 Ω Sine Wave +13.00 dBm 100.000 kHz 0 dB ± 0.086 dB

50 Ω Sine Wave +13.00 dBm 200.000 kHz 0 dB ± 0.086 dB

50 Ω Sine Wave +13.00 dBm 500.000 kHz 0 dB ± 0.086 dB

50 Ω Sine Wave +13.00 dBm 1.500 MHz 0 dB ± 0.086 dB

50 Ω Sine Wave +13.00 dBm 5.000 MHz 0 dB ± 0.086 dB

Q 50 Ω Sine Wave +13.00 dBm 10.000 MHz 0 dB ± 0.086 dB

50 Ω Sine Wave +13.00 dBm 25.000 MHz 0 dB ± 0.177 dB

50 Ω Sine Wave +13.00 dBm 40.000 MHz 0 dB ± 0.177 dB

Q 50 Ω Sine Wave +13.00 dBm 50.000 MHz 0 dB ± 0.177 dB

50 Ω Sine Wave +13.00 dBm 60.000 MHz 0 dB ± 0.423 dB

50 Ω Sine Wave +13.00 dBm 65.000 MHz 0 dB ± 0.423 dB

50 Ω Sine Wave +13.00 dBm 70.000 MHz 0 dB ± 0.423 dB

50 Ω Sine Wave +13.00 dBm 75.000 MHz 0 dB ± 0.423 dB

Q 50 Ω Sine Wave +13.00 dBm 80.000 MHz 0 dB ± 0.423 dB

4 Compare the measured output to the test limits shown in the table.

Chapter 4 Calibration Procedures

+20 dB Range Flatness Verification

This procedure checks the high frequency ac amplitude flatness above 100 kHz on the +20 dB attenuator range.

1 Connect the power meter to measure the output voltage of the

instrument as shown below.

2 Set the power meter reference level to equal to the calculated

100kHz_20dB_offset value. This sets the power meter to directly read the flatness error specification. 100kHz_20dB_offset is calculated on the Amplitude and Flatness Verification Worksheet.

Caution Most power meters will require an attenuator or special power head to

measure the +20 dB output.

Chapter 4 Calibration Procedures

+20 dB Range Flatness Verification

3 Set the instrument to each output described in the table below and

measure the output amplitude with the power meter. Press to set the output impedance to 50Ω. Be sure the output is enabled

Agilent 33250A Measurement

Output Setup Function Amplitude Frequency Nominal Error

Q 50 Ω Sine Wave +23.90 dBm 100.000 kHz 0 dB ± 0.086 dB

50 Ω Sine Wave +23.90 dBm 200.000 kHz 0 dB ± 0.086 dB

50 Ω Sine Wave +23.90 dBm 500.000 kHz 0 dB ± 0.086 dB

50 Ω Sine Wave +23.90 dBm 1.500 MHz 0 dB ± 0.086 dB

50 Ω Sine Wave +23.90 dBm 5.000 MHz 0 dB ± 0.086 dB

Q 50 Ω Sine Wave +23.90 dBm 10.000 MHz 0 dB ± 0.086 dB

50 Ω Sine Wave +23.90 dBm 25.000 MHz 0 dB ± 0.177 dB

50 Ω Sine Wave +23.90 dBm 40.000 MHz 0 dB ± 0.177 dB

Q 50 Ω Sine Wave +23.90 dBm 50.000 MHz 0 dB ± 0.177 dB

50 Ω Sine Wave +23.90 dBm 60.000 MHz 0 dB ± 0.423 dB

50 Ω Sine Wave +23.90 dBm 65.000 MHz 0 dB ± 0.423 dB

50 Ω Sine Wave +23.90 dBm 70.000 MHz 0 dB ± 0.423 dB

50 Ω Sine Wave +23.90 dBm 75.000 MHz 0 dB ± 0.423 dB

Q 50 Ω Sine Wave +23.90 dBm 80.000 MHz 0 dB ± 0.423 dB

4 Compare the measured output to the test limits shown in the table.

Chapter 4 Calibration Procedures

Calibration Security

See “To Unsecure and Secure for Calibration”, on page 41 for a procedure to enter the security code.

• The security code is set to from the factory. The security code is stored in non-volatile memory, and does not change when power has been off, after a Factory Reset (

*RST command), or after an Instrument Preset (SYSTem:PRESet

command).

Note: If you forget your security code, you can disable the security feature by applying a temporary short inside the instrument as described on the following page.

AT33250A when the instrument is shipped

Chapter 4 Calibration Procedures

Calibration Security

To Unsecure the Instrument Without the Security Code

To unsecure the instrument without the correct security code, follow the steps below. See “To Unsecure and Secure for Calibration” on page 41. See “Electrostatic Discharge (ESD) Precautions” on page 133 before beginning this procedure.

1 Disconnect the power cord and all input connections.

2 Remove the instrument cover. See “Disassembly” on page 140.

3 Remove the main power supply.

4 Apply a temporary short between the two exposed metal pads on the

A1 assembly. The general location is shown in the figure below. On the PC board, the pads are marked CAL ORIDE.

5 Apply power and turn on the instrument.

WARNING Be careful not to touch the power line connections or high voltages on the

power supply module.

6 The display will show the message “Calibration security has been

disabled”. The instrument is now unsecured.

7 Turn off the instrument and remove the power cord.

8 Reassemble the instrument.

Now you can enter a new security code, see “To Unsecure and Secure for Calibration”, on page 41. Be sure you record the new security code.

Chapter 4 Calibration Procedures

Calibration Message

The instrument allows you to store one message in calibration memory. For example, you can store such information as the date when the last calibration was performed, the date when the next calibration is due, the instrument’s serial number, or even the name and phone number of the person to contact for a new calibration.

You can record a calibration message only from the remote interface and only when the instrument is unsecured.

You can read the message from either the front-panel or over the remote interface. You can read the calibration message whether the instrument is secured or unsecured. Reading the calibration message from the front panel is described on “To Read the Calibration Information”, on page 40.

Calibration Count

You can query the instrument to determine how many calibrations have been performed. Note that your instrument was calibrated before it left the factory. When you receive your instrument, read the count to determine its initial value. The count value increments by one for each calibration point, and a complete calibration may increase the value by many counts. See “To Read the Calibration Information”, on page 40.

Chapter 4 Calibration Procedures

General Calibration/Adjustment Procedure

The following procedure is the recommended method to complete an instrument calibration. This procedure is an overview of the steps required for a complete calibration. Additional details for each step in this procedure are given in the appropriate sections of this chapter.

1 Read “Test Considerations” on page 54.

2 Unsecure the instrument for calibration (see page 68).

3 Perform the verification tests, beginning on page page 55, to characterize

the instrument (incoming data).

4 Press on the front panel.

5 Select the “Test / Cal” menu.

6 Select Perform Cal.

7 Enter the Setup Number for the procedure being performed. The default

setup number is “1” and, from the front panel, the number will increment as the procedures are performed.

8 Select BEGIN.

9 For setups that require an input, adjust the value shown in the display

to the measured value and select ENTER VALUE.

10 The setup will automatically advance to the next required value.

Note To cancel the adjustment procedure, select CANCEL STEP. The display

will return to the setup number entry.

11 When finished, select END CAL.

12 Secure the instrument against calibration.

13 Note the new security code and calibration count in the instrument’s

maintenance records.

Chapter 4 Calibration Procedures

Aborting a Calibration in Progress

Sometimes it may be necessary to abort a calibration after the procedure has already been initiated. You can abort a calibration at any time by turning off the power. When performing a calibration from the remote interface, you can abort a calibration by issuing a remote interface device clear message followed by a

The instrument stores calibration constants at the end of each adjustment procedure. If you lose power, or otherwise abort an adjustment in progress, you will only need to perform the interrupted adjustment procedure again.

Caution If you abort a calibration in progress when the instrument is attempting

to write new calibration constants to EEPROM, you may lose all calibration constants for the function. Typically, upon re-applying power, the instrument will report error “705 Calibration Aborted”.

*RST.

Sequence of Adjustments

The adjustment sequence shown in the following sections of this chapter is recommended to minimize the number of test equipment set-up and connection changes.

You may perform individual adjustments as necessary. Setups 1 through 7 must be performed in order and must be performed before any other setup procedure.

Note If you have repaired the output amplifier circuitry (U1903, U1904, and

associated components) you should perform the “Output Amplifier Adjustment (Optional)”, on page 90 before beginning any other adjustment procedures.

Chapter 4 Calibration Procedures

Self-Test

Self-Test is performed as the first step to ensure the instrument is in working order before beginning any additional adjustments.

1 Press on the front panel. Select Perform Cal on the “Test / Cal”

menu. Enter setup number “1” and select BEGIN.

Setup

1 Performs the Self-test. The Main Output is disabled during test.

2 If the instrument fails any self-test, you must repair the instrument

before continuing the adjustment procedures.

Chapter 4 Calibration Procedures

Frequency (Internal Timebase) Adjustment

The function generator stores a calibration constant that sets the TCXO to output exactly 10 MHz.

1 Set the frequency counter resolution to better than 0.1 ppm and the

input termination to 50Ω (if your frequency counter does not have a 50Ω input termination, you must provide an external termination). Make the connections shown below.

2 Use a frequency counter to measure the output frequency for each setup

in the following table.

Nominal Signal

Setup Frequency Amplitude

2 <10 MHz 1 Vpp Output frequency is slightly less than 10 MHz

3 >10 MHz 1 Vpp Output frequency is slightly more than 10 MHz

4 ~10 MHz 1 Vpp Output frequency should be near 10 MHz

5* 10 MHz 1 Vpp Output frequency should be 10 MHz ±0.5 ppm

* Constants are stored after completing this setup.

3 Using the numerical keypad or knob, adjust the displayed frequency at

each setup to match the measured frequency. Select ENTER VALUE.

4 After performing setup 5:

a. If your calibration procedures require you to verify the adjustment just

made, exit the calibration menu and perform “Internal Timebase Verification”, on page 60.

b. If you are making all the adjustments and then verifying the instrument’s

performance, continue with the next procedure in this chapter.

Chapter 4 Calibration Procedures

Internal ADC Adjustment

The function generator stores calibration constants related to the gain and offset of the internal ADC. Setup 6 must always be performed before any other adjustments are attempted. The internal ADC is then used as a source for the calibration constants generated in setup 7.

1 Make the connections as shown below.

Modulation In

2 Set the DMM to display 5

Record the measurement.

3 Enter the following setup and use the numeric keypad or knob to enter

the measured value of the dc source.

Nominal Signal

½ digits and measure the dc value.

Setup DC level

6* ~1 Vdc ±10% Calibrates the internal ADC.

* Constants are stored after completing this setup.

4 Disconnect all cables from the rear panel Modulation In connector.

Chapter 4 Calibration Procedures

Output Impedance Adjustment

5 Enter and begin the following setup.

Setup

7* Self-calibration. The Main Output is disabled during test.

* Constants are stored after completing this setup.

6 There are no specific operational verification tests for setups 6 and 7

since the constants generated affect almost all behavior of the instrument. Continue with the next adjustment procedure in this chapter.

Output Impedance Adjustment

The function generator stores calibration constants for the output impedance. The output impedance constants are generated with and without the distortion filter and using all five attenuator paths.

1 Set the DMM to measure offset-compensated, four-wire Ohms. Set the

DMM to use 100 NPLC integration. Make the connections as shown below.

Chapter 4 Calibration Procedures

Output Impedance Adjustment

2 Use the DMM to make a resistance measurement at the front panel

Output connector for each setup in the following table. The expected measured value is approximately 50Ω.

Setup

8* -30 dB range with distortion filter

9* -20 dB range with distortion filter

10* -10 dB range with distortion filter

11* 0 dB range with distortion filter

12* +10 dB range with distortion filter

13* -30 dB range without distortion filter

14* -20 dB range without distortion filter

15* -10 dB range without distortion filter

16* 0 dB range without distortion filter

17* +10 dB range without distortion filter

* Constants are stored after completing this setup.

3 Using the numeric keypad or knob, adjust the displayed impedance at

each setup to match the measured impedance. Select ENTER VALUE.

4 There are no specific operational verification tests for Output Impedance.

Continue with the next adjustment procedure in this chapter.

Chapter 4 Calibration Procedures

AC Amplitude (high-impedance) Adjustment

The function generator stores a calibration constant for each highimpedance attenuator path. The gain coefficient of each path is calculated using two measurements; one with the waveform DAC at the + output and one with waveform DAC at the – output. The setups, therefore, must be performed in pairs.

1 Connect the DMM as shown below.

Chapter 4 Calibration Procedures

AC Amplitude (high-impedance) Adjustment

2 Use the DMM to measure the dc voltage at the front-panel Output

connector for each setup in the following table.

Nominal Signal

Setup DC level

18 +0.015 V Output of -30 dB range

19* -0.015 V Output of -30 dB range

20 +0.05 V Output of -20 dB range

21* -0.05 V Output of -20 dB range

22 +0.15 V Output of -10 dB range

23* -0.15 V Output of -10 dB range

24 +0.50 V Output of 0 dB range

25* -0.50 V Output of 0 dB range

26 +0.15 V Output of -10 dB range (Amplifier In)

27* -0.15 V Output of -10 dB range (Amplifier In)

28 +0.50 V Output of 0 dB range (Amplifier In)

29* -0.50 V Output of 0 dB range (Amplifier In)

30 +1.5 V Output of +10 dB range (Amplifier In)

31* -1.5 V Output of +10 dB range (Amplifier In)

32 +5 V Output of +20 dB range (Amplifier In)

33* -5 V Output of +20 dB range (Amplifier In)

* Constants are stored after completing this setup.

3 Using the numeric keypad or knob, adjust the displayed voltage at each

setup to match the measured voltage. Select ENTER VALUE. (Entered values are rounded to the nearest 100 µV.)

4 After performing setup 33:

a. If your calibration procedures require you to verify the adjustment

just made, exit the calibration menu and perform “AC Amplitude (highimpedance) Verification”, on page 61.

b. If you are making all the adjustments and then verifying the instrument’s

performance, continue with the next procedure in this chapter.

Chapter 4 Calibration Procedures

Low Frequency Flatness Adjustment

The Low Frequency Flatness adjustment calculates the flatness response of 3 attenuator paths with the Elliptical filter and 2 attenuator paths with the Linear Phase filter.

1 Set the DMM to measure Vrms. Make the connections shown on page 78.

2 Use the DMM to measure the output voltage for each of the setups in the

table below.

Nominal Signal

Setup Frequency Amplitude

34* 1 kHz 0.56 Vrms Flatness for 0 dB, Elliptical Filter

35* 100 kHz 0.56 Vrms Flatness for 0 dB, Elliptical Filter

36* 1 kHz 0.56 Vrms Flatness for 0 dB, Linear Phase Filter

37* 100 kHz 0.56 Vrms Flatness for 0 dB, Linear Phase Filter

38* 1 kHz 1.7 Vrms Flatness for +10 dB, Elliptical Filter

39* 100 kHz 1.7 Vrms Flatness for +10 dB, Elliptical Filter

40* 1 kHz 5.6 Vrms Flatness for +20 dB, Elliptical Filter

41* 100 kHz 5.6 Vrms Flatness for +20 dB, Elliptical Filter

42* 1 kHz 5.6 Vrms Flatness for +20 dB, Linear Phase Filter

43* 100 kHz 5.6 Vrms Flatness for +20 dB, Linear Phase Filter

* Constants are stored after completing this setup.

3 Using the numeric keypad or knob, adjust the displayed voltage at each

setup to match the measured voltage. Select ENTER VALUE.

4 After performing setup 43:

a. If your calibration procedures require you to verify the adjustment just

made, exit the calibration menu and perform “Low Frequency Flatness Verification”, on page 62.

b. If you are making all the adjustments and then verifying the instrument’s

performance, continue with the next procedure in this chapter.

Chapter 4 Calibration Procedures

0 dB Range Flatness Adjustments

1 Connect the power meter as shown on page 83.

2 Use the power meter to measure the output amplitude for each of the

setups in the table below.

Note Setup 44 establishes the power meter reference for all the remaining

setups in this table. You must always perform setup 44 before any of the following setups.

Nominal Signal

Setup Frequency Amplitude

44* 100 kHz 0.28 Vrms 2 dBm Power Meter Reference for 0 dB Range

45* 200 kHz 0.28 Vrms 2 dBm Flatness for 0 dB, Elliptical Filter

46* 500 kHz 0.28 Vrms 2 dBm Flatness for 0 dB, Elliptical Filter

47* 1.5 MHz 0.28 Vrms 2 dBm Flatness for 0 dB, Elliptical Filter

48* 5 MHz 0.28 Vrms 2 dBm Flatness for 0 dB, Elliptical Filter

49* 10.1 MHz 0.28 Vrms 2 dBm Flatness for 0 dB, Elliptical Filter

50* 25.1 MHz 0.28 Vrms 2 dBm Flatness for 0 dB, Elliptical Filter

51* 40.1 MHz 0.28 Vrms 2 dBm Flatness for 0 dB, Elliptical Filter

52* 50.1 MHz 0.28 Vrms 2 dBm Flatness for 0 dB, Elliptical Filter

53* 60.1 MHz 0.28 Vrms 2 dBm Flatness for 0 dB, Elliptical Filter

54* 65.1 MHz 0.28 Vrms 2 dBm Flatness for 0 dB, Elliptical Filter

55* 70.1 MHz 0.28 Vrms 2 dBm Flatness for 0 dB, Elliptical Filter

56* 75.1 MHz 0.28 Vrms 2 dBm Flatness for 0 dB, Elliptical Filter

57* 79.9 MHz 0.28 Vrms 2 dBm Flatness for 0 dB, Elliptical Filter

* Constants are stored after completing this setup.

Continued on next page...

Chapter 4 Calibration Procedures

0 dB Range Flatness Adjustments

Nominal Signal

Setup Frequency Amplitude

58* 200 kHz 0.28 Vrms 2 dBm Flatness for 0 dB, Linear Phase

59* 500 kHz 0.28 Vrms 2 dBm Flatness for 0 dB, Linear Phase

60* 1.5 MHz 0.28 Vrms 2 dBm Flatness for 0 dB, Linear Phase

61* 5 MHz 0.28 Vrms 2 dBm Flatness for 0 dB, Linear Phase

62* 10.1 MHz 0.28 Vrms 2 dBm Flatness for 0 dB, Linear Phase

63* 25.1 MHz 0.28 Vrms 2 dBm Flatness for 0 dB, Linear Phase

64 25.1 MHz 0.15 Vrms –4 dBm Flatness reference measurement

65* 79.9 MHz <0.15 Vrms –4 dBm Flatness high frequency measurement

* Constants are stored after completing this setup.

3 Using the numeric keypad or knob, adjust the displayed amplitude

at each setup to match the measured amplitude (in dBm). Select ENTER VALUE.

4 After performing setup 65:

a. If your calibration procedures require you to verify the adjustment just

made, exit the calibration menu and perform “0 dB Range Flatness Verification”, on page 63.

b. If you are making all the adjustments and then verifying the instrument’s

performance, continue with the next procedure in this chapter.

Chapter 4 Calibration Procedures

+10 dB Range Flatness Adjustments

Note The Linear Phase path is not adjusted. It is approximated using the other

path’s values.

1 Connect the power meter as shown below.

2 Use the power meter to measure the output amplitude for each of the

setups in the table on the next page.

Note Setup 66 establishes the power meter reference for all the remaining

setups in this table. You must always perform setup 66 before any of the following setups.

Chapter 4 Calibration Procedures

+10 dB Range Flatness Adjustments

Nominal Signal

Setup Frequency Amplitude

66* 100 kHz 0.9 Vrms 12 dBm Power Meter Reference for +10 dB Range

67* 200 kHz 0.9 Vrms 12 dBm Flatness for +10 dB, Elliptical Filter

68* 500 kHz 0.9 Vrms 12 dBm Flatness for +10 dB, Elliptical Filter

69* 1.5 MHz 0.9 Vrms 12 dBm Flatness for +10 dB, Elliptical Filter

70* 5 MHz 0.9 Vrms 12 dBm Flatness for +10 dB, Elliptical Filter

71* 10.1 MHz 0.9 Vrms 12 dBm Flatness for +10 dB, Elliptical Filter

72* 25.1 MHz 0.9 Vrms 12 dBm Flatness for +10 dB, Elliptical Filter

73* 40.1 MHz 0.9 Vrms 12 dBm Flatness for +10 dB, Elliptical Filter

74* 50.1 MHz 0.9 Vrms 12 dBm Flatness for +10 dB, Elliptical Filter

75* 60.1 MHz 0.9 Vrms 12 dBm Flatness for +10 dB, Elliptical Filter

76* 65.1 MHz 0.9 Vrms 12 dBm Flatness for +10 dB, Elliptical Filter

77* 70.1 MHz 0.9 Vrms 12 dBm Flatness for +10 dB, Elliptical Filter

78* 75.1 MHz 0.9 Vrms 12 dBm Flatness for +10 dB, Elliptical Filter

79* 79.9 MHz 0.9 Vrms 12 dBm Flatness for +10 dB, Elliptical Filter

* Constants are stored after completing this setup.

3 Using the numeric keypad or knob, adjust the displayed amplitude at

each setup to match the measured amplitude (in dBm). Select ENTER VALUE.

4 After performing setup 79:

a. If your calibration procedures require you to verify the adjustment just

made, exit the calibration menu and perform “+10 dB Range Flatness Verification”, on page 65.

b. If you are making all the adjustments and then verifying the instrument’s

performance, continue with the next procedure in this chapter.

Chapter 4 Calibration Procedures

+20 dB Range Flatness Adjustment

Caution Most power meters will require an attenuator (-20 dB) or special power

head to measure the +20 dB output.

Be sure to correct the measurements for the specifications of the attenuator you use. For example, if the nominal attenuator value is –20 dB at the specified frequency, you must add 20 dB to the power meter reading before entering the value.

1 Make the connections as shown below.

2 Use the power meter to measure the output amplitude for each of the

setups in the table on the next page.

Note Setup 80 establishes the power meter reference for all the remaining

setups in this table. You must always perform setup 80 before any of the following setups.

Nominal Signal

Setup Frequency Amplitude

80* 100 kHz 2.8 Vrms 22 dBm Power Meter Reference

81* 200 kHz 2.8 Vrms 22 dBm Flatness for +20 dB, Elliptical Filter

82* 500 kHz 2.8 Vrms 22 dBm Flatness for +20 dB, Elliptical Filter

83* 1.5 MHz 2.8 Vrms 22 dBm Flatness for +20 dB, Elliptical Filter

* Constants are stored after completing this setup.

Continued on next page...

Chapter 4 Calibration Procedures

+20 dB Range Flatness Adjustment

Nominal Signal

Setup Frequency Amplitude

84* 5 MHz 2.8 Vrms 22 dBm Flatness for +20 dB, Elliptical Filter

85* 10.1 MHz 2.8 Vrms 22 dBm Flatness for +20 dB, Elliptical Filter

86* 25.1 MHz 2.8 Vrms 22 dBm Flatness for +20 dB, Elliptical Filter

87* 40.1 MHz 2.8 Vrms 22 dBm Flatness for +20 dB, Elliptical Filter

88* 50.1 MHz 2.8 Vrms 22 dBm Flatness for +20 dB, Elliptical Filter

89* 60.1 MHz 2.8 Vrms 22 dBm Flatness for +20 dB, Elliptical Filter

90* 65.1 MHz 2.8 Vrms 22 dBm Flatness for +20 dB, Elliptical Filter

91* 70.1 MHz 2.8 Vrms 22 dBm Flatness for +20 dB, Elliptical Filter

92* 75.1 MHz 2.8 Vrms 22 dBm Flatness for +20 dB, Elliptical Filter

93* 79.9 MHz 2.8 Vrms 22 dBm Flatness for +20 dB, Elliptical Filter

94* 200 kHz 2.8 Vrms 22 dBm Flatness for +20 dB, Linear Phase Filter

95* 500 kHz 2.8 Vrms 22 dBm Flatness for +20 dB, Linear Phase Filter

96* 1.5 MHz 2.8 Vrms 22 dBm Flatness for +20 dB, Linear Phase Filter

97* 5 MHz 2.8 Vrms 22 dBm Flatness for +20 dB, Linear Phase Filter

98* 10.1 MHz 2.8 Vrms 22 dBm Flatness for +20 dB, Linear Phase Filter

99* 25.1 MHz 2.8 Vrms 22 dBm Flatness for +20 dB, Linear Phase Filter

100 60.1 MHz 3.4 Vrms 24 dBm Flatness reference measurement

101* 79.9 MHz ~3.2 Vrms 23 dBm Flatness high frequency measurement

* Constants are stored after completing this setup.

3 Using the numeric keypad or knob, adjust the displayed amplitude at

each setup to match the measured amplitude (in dBm). Select ENTER VALUE.

4 After performing setup 101:

a. If your calibration procedures require you to verify the adjustment just

made, exit the calibration menu and perform “+20 dB Range Flatness Verification”, on page 66.

b. If you are making all the adjustments and then verifying the instrument’s

performance, continue with the next procedure in this chapter.

Chapter 4 Calibration Procedures

Pulse Width (Trailing Edge Delay) Adjustment

The function generator stores calibration constants used to set the trailing edge delay (see the discussion on page 110). These setups place the instrument in pulse mode (at 8 MHz). Setup 102 must be performed immediately prior to setup 103.

1 Set the oscilloscope to use averaging to determine the pulse width.

Set the oscilloscope to 50Ω input termination (if your oscilloscope does not have a 50Ω input termination, you must provide an external termination). Make the connections as shown below.

2 Use the oscilloscope to measure the pulse width of signal at the front-

panel Output terminal for each of the following setups.

Nominal Signal Measurement: Pulse Width(s)

Setup Freq Amplitude Pulse Width

102 8 MHz 1 Vpp 30 ns Narrow pulse width

103* 8 MHz 1 Vpp 42 ns Wide pulse width

* Constants are stored after completing this setup.

3 Using the numeric keypad or knob, adjust the displayed pulse width at

each setup to match the measured pulse width. Select ENTER VALUE.

4 There are no specific operational verification tests for the Pulse Width

Adjustment. Continue with the next adjustment procedure in this chapter.

Chapter 4 Calibration Procedures

Pulse Edge Time Adjustment

The function generator stores calibration constants used to calculate the slope and offset of the edge time DAC outputs. These setups output 100 Hz pulses with 5 ms pulse widths. The setups, following the first three, must be done in pairs (i.e., 107 immediately before 108).

1 Set the oscilloscope to 50Ω input termination (if your oscilloscope does

not have a 50Ω input termination, you must provide an external termination). Measure the rise time from the 10% to 90% points on the waveform. Make the connections shown on page 87.

2 Use an oscilloscope to measure the rise time of the output signal at the

front-panel Output connector for each setup in the following table.

Nominal Signal

Setup Freq Amplitude Rise Time

104 100 Hz 1 Vpp 3.2 ns Fastest transition range 0

105* 100 Hz 1 Vpp 4.5 ns Mid transition range 0

106* 100 Hz 1 Vpp 64 ns Slowest transition range 0

107 100 Hz 1 Vpp 8 ns Fastest transition range 1

108* 100 Hz 1 Vpp 241 ns Slowest transition range 1

109 100 Hz 1 Vpp 161 ns Fastest transition range 2 110* 100 Hz 1 Vpp 4.9 µs Slowest transition range 2 111 100 Hz 1 Vpp 2.6 µs Fastest transition range 3 112* 100 Hz 1 Vpp 82 µs Slowest transition range 3 113 100 Hz 1 Vpp 57 µs Fastest transition range 4

114* 100 Hz 1 Vpp 1.75 ms Slowest transition range 4

* Constants are stored after completing this setup.

Rise time measured can vary greatly from the nominal values shown.

3 Using the numeric keypad or knob, adjust the displayed rise time

(10% to 90%) at each setup to match the measured rise time. Select ENTER VALUE.

4 There are no specific operational verification tests for the Pulse Edge Time

Adjustment. Continue with the next adjustment procedure in this chapter.

Chapter 4 Calibration Procedures

Duty Cycle Adjustment

The function generator stores a calibration constant used to calculate the square wave duty cycle. This setup outputs a 25.1 MHz square wave. The output frequency in this procedure is chosen to avoid artifacts of DDS signal generation and internal clock frequencies.

The “Internal ADC Adjustment”, on page 75 must be completed before doing this procedure.

1 Set the oscilloscope to 50Ω input termination (if your oscilloscope

does not have a 50Ω input termination, you must provide an external termination). Make the connections shown on page 87.

2 Use an oscilloscope to measure the duty cycle of the signal at the front-

panel Output connector.

Nominal Signal

Setup Freq Amplitude Duty Cycle

115* 25.1 MHz 1 Vpp 50% Enter measured duty cycle

* Constants are stored after completing this setup.

3 Using the numeric keypad or knob, adjust the displayed duty cycle at

each setup to match the measured duty cycle. Select ENTER VALUE.

4 There are no specific operational verification tests for the

Duty Cycle Adjustment.

5 Secure the instrument against further adjustments as described

on page 43.

You have now completed the recommended adjustment procedures. You should now verify the output specifications of the instrument using the “Performance Verification Tests”, on page 55.

Chapter 4 Calibration Procedures

Output Amplifier Adjustment (Optional)

This adjustment should only be performed if repairs have been made the output amplifier circuitry (U1903, U1904, and associated components). This adjustment is performed at the factory and re-adjustment is not needed or recommended.

Note You must perform a complete calibration of the instrument following

this adjustment.

1 Disconnect the power cord and all input connections.

2 Remove the instrument cover. See “Disassembly”, on page 140.

3 Attach the power cord. Press and hold the “1” button and then turn on

the instrument. Be careful not to touch the power line connections.

4 The display shows a bar graph.

5 Use a long, small, flat-bladed screwdriver to adjust R1959 to minimize

the length of the bar in the display. The adjustment tool can reach R1959 through the slot in the sheet metal as shown.

6 Turn off the instrument and remove the power cord.

7 Re-assemble the instrument.

8 Perform the Adjustment and Verification procedures.

Chapter 4 Calibration Procedures

Calibration Errors

The following errors are failures that may occur during a calibration. System error messages are described in chapter 5 of the Agilent 33250A User’s Guide. Self-test error messages are described in this manual beginning on page 137.

701 Calibration error; security defeated by hardware jumper

If you short the calibration secure jumper while turning ON the instrument, this error will occur indicating the security password has been overwritten.

702 Calibration error; calibration memory is secured

703 Calibration error; calibration memory is secured

704 Calibration error; secure code provided was invalid

705 Calibration error; calibration aborted

706 Calibration error; value out of range

You have typed in a value that was unexpected by the calibration firmware. For example, if a number is expected such a 50.XX ohms, and you enter 10 ohms, that number is outside the expected range of valid inputs.

707 Calibration error; value out of range

Occurs during the ADC Adjustment, setup 6, if the 1 Volt input voltage is too high.

850 Calibration error; set up is invalid

You have selected an invalid calibration setup number.

851 Calibration error; set up is out of order

Certain calibration steps require a specific beginning and ending sequence. You may not enter into the middle of a sequence of calibration steps.

Theory of Operation

This chapter provides descriptions of the circuitry shown on the schematics in chapter 9.

• Block Diagram, on page 95

• Main Power Supply, on page 97

• On-Board Power Supplies, on page 98

• Waveform DAC and Filters, on page 100

• Digital Waveform, Pulse, and Sync, on page 101

• Digital Waveform Translator, on page 104

• Amplitude Multiplier, on page 106

• Main Output Circuitry, on page 107

• System ADC, on page 110

• System DAC, on page 112

• Synthesis IC, on page 113

• Timebase, on page 115

• Phase Locked Loops, on page 116

• Clock Divider, on page 118

• Trigger and Delay, on page 120

• Waveform RAM, on page 122

• Synchronous Multiplexer, on page 123

• Main Processor, on page 124

• Main Gate Array, on page 125

• DSP and Gateway, on page 126

• Earth-Referenced Logic, on page 126

• Front Panel, on page 127

Chapter 5 Theory of Operation

Block Diagram

A block diagram is shown on the next page. The function generator’s circuits may be divided into three main categories: power supplies, analog circuits, and digital circuits. Each portion of the block diagram is described in the following sections.

The line input voltage is filtered, and then applied to the main power supply. The main power supply provides all power to the instrument. Secondary power supplies are contained on the main circuit board. The secondary supplies control the fan, create the –2.1 V and +3.3 V voltages, and provide the isolated +5 V supply.

The analog circuitry begins at the Waveform DAC and continues to the main output. Sine, ramp, noise, and arbitrary waveforms pass directly from the Waveform DAC to the main output circuitry. Square waves and pulses are formed in the digital waveform and variable rate edge and level translation circuits.

The digital circuitry contains all the waveform generation circuitry and waveform memory. The main CPU and communications CPU (outguard) are also included.

Conventions Used on Schematics and in this Discussion

Major signal and control lines are marked with a name in uppercase. If the name is followed by an * (for example, TRIG_SYNC*), the line is inverted logic. If the name is followed by a lowercase e, (for example, TRIGe), the line is the ECL-level version of a TLL or CMOS signal.

Agilent 33250A Block Diagram

Chapter 5 Theory of Operation

Main Power Supply

Power Supplies

Main Power Supply

The main power supply is a switching supply. No schematic is given for this supply since it should be replaced as a unit. It features a universal input, eliminating the need to set power line voltage or frequency.

The main supply provides the following voltages to the main board:

• +5 V (for logic and analog circuitry)

• +16 V, –16 V (for analog circuitry)

• –5.2 V (for ECL logic and analog circuitry)

• +12 V isolated (for fan and earth-referenced logic)

• +12 V standby (for power switch and over-temperature shutdown circuitry)

The main supply uses an electronic power switch, controlled by logic on the main board, to turn the supplies on or off. The +12 V standby power is always available when line power is applied. All the power supply outputs can be checked on the main board.

Chapter 5 Theory of Operation

On-Board Power Supplies

See “A1 Power Supply Schematic” on page 204.

The on-board power supply controls the on/off state of the power supply and conditions the main supplies for use by the analog and digital circuits. Over-temperature protection is also provided.

The main supply provides a +12 V standby power supply that is used by the power on/off circuitry. The electronic power switch is controlled by the PWR_SWITCH* line. This line is grounded when the front-panel power switch is pushed and turns on Q2004 through R2026.

Pressing the power switch turns on Q2004, and C2043 and C2047 begin to charge up. Depending upon the state of relay K2001, R2025 will be in parallel with either R2023 or R2024, so one of the capacitors will charge much faster than the other. The charged capacitor turns on either Q2006 or Q2008 and energizes the coil of K2001, changing the relay to the opposite state. Repeatedly pushing the power switch toggles the relay from one state to the other. In the ON state, PWR_ON* is grounded through Q2009, turning on the main power supply.

Q2009 can turn off the main supplies if an over-temperature condition is sensed by U2006, which is powered by the +12 V standby power supply. U2006 has two trip points for over-temperature. The first trip point is set at approximately 85 °C and is asserted by OUT 1. This is a warning to the microprocessor and this condition can be read via GPIB in the status byte. The second trip point is set at approximately 90 °C and is an actual over-temperature condition that asserts OUT 2. This turns off Q2009 and shuts off the main supplies.

The actual temperature sensed by U2006 can be read by the microprocessor through the MEAS_TEMP signal. This reading is used during the calibration and adjustment process.

Secondary logic supplies are derived from the main power supply’s +5 V (VCC). Switching regulator U2004 provides the +3.3 V supply (VDD) for the synthesis IC and waveform memory. U2005 provides the –2.1 V ECL termination supply (VTT).

The +12 V earth-referenced supply, +12V_ER, is reduced to +5 V by voltage regulator U2003. This is the earth-referenced logic power supply (+5_ER).

Chapter 5 Theory of Operation

On-Board Power Supplies

The variable-speed fan is driven by a temperature-controlled switching regulator which is powered by +12V_ER. Comparator U2002-A is configured as an oscillator whose output (at C2013) is a triangle wave. Thermistor R2016 senses the incoming air temperature and U2001-A converts it to a voltage. U2002-B compares this voltage to the triangle wave and outputs a square wave whose duty cycle varies with temperature. The square wave is buffered by U104-C and Q2001 and then filtered by L2003 and C2004 to create a dc voltage that varies with the temperature and is used to power the fan. Below 30 °C, the fan voltage is set to approximately 7 volts by R2003 and R2015 (since CR2004 is reversebiased). Above 50 °C, U2001-A’s output voltage is below the minimum voltage of the triangle wave, keeping Q2001 on constantly and applying full voltage to the fan.

The PWR_FAIL* line is provided by the main supply to indicate brownout or sagging line input condition. The microprocessor uses this line to initiate saving the current state of the instrument in non-volatile memory.

Chapter 5 Theory of Operation

Waveform DAC and Filters

Analog Circuitry

The analog circuitry begins at the Waveform DAC and continues to the main output.

Sine, ramp, noise, and arbitrary waveforms pass directly from the Waveform DAC to the main output circuitry. Square waves and pulses are formed in the digital waveform and variable-rate level translation circuits.

Waveform DAC and Filters

See “A1 Waveform DAC, Filters, and Comparator Schematic” on page 201.

The 12-bit waveform DAC, U1701, is loaded with data by the Synchronous Multiplexer of the digital circuitry. The most significant bit of this data is inverted by U1401-B to convert the 2’s complement value in memory to the offset-binary representation required by the DAC. Data is clocked at a 200 MHz rate through differential clock inputs WFDAC_CLK±. The waveform DAC clock is out of phase with the LOGIC_CLK to provide ample setup and hold times for the data.

The DAC output, at pins 17 and 18, is centered at –250 mV and ranges from 0 mV to –500 mV full scale.

Latching relay K1701 connects the DAC output to one of two filters:

•A 9

•A 7

Relay K1701 is driven by the SET_STEP and SET_SINE lines from U306.

The output of the selected filter is applied to amplifier U1703. U1703 has a gain of 4.3 and the output is level shifted to center at ground potential. The output ranges from –1.1 V to +1.1 V. U1702 uses VREF (+2.5 V) to provide an output level appropriate to shift the waveform DAC output to center around ground.

order elliptical filter with a cutoff frequency of 85 MHz.

This filter includes sine and square waves.

order linear-phase filter with a cutoff frequency of 50 MHz. It is

used for ramp, noise, and arbitrary waveforms. It is also used for sine and square waves in burst mode.

100

sin(x)/x correction. It is used for continuous

Agilent 33250A Service Guide

Specifications and Main Features

Frequently Asked Questions

User Manual

Agilent 33250A at a Glance

The Front Panel at a Glance

The Front-Panel Display at a Glance

Front-Panel Number Entry

The Rear Panel at a Glance

In This Book

Contents

Quick Start

To Prepare the Function Generator for Use

To Adjust the Carrying Handle

To Set the Output Frequency

To Set the Output Amplitude

To Set a DC Offset Voltage

To Set the Duty Cycle

To Configure a Pulse Waveform

To View a Waveform Graph

To Output a Stored Arbitrary Waveform

To Use the Built-In Help System

To Rack Mount the Function Generator

Front-Panel Menu Operation

Front-Panel Menu Reference

To Reset the Function Generator

To Select the Output Termination

To Read the Calibration Information

To Unsecure and Secure for Calibration

To Unsecure for Calibration

To Secure After Calibration

To Store the Instrument State

To Configure the Remote Interface

Calibration Procedures

Agilent Technologies Calibration Services

Calibration Interval

Adjustment is Recommended

Time Required for Calibration

Automating Calibration Procedures

Recommended Test Equipment

Test Considerations

Performance Verification Tests

Self-Test

Quick Performance Check

Amplitude and Flatness Verification Procedures

Amplitude and Flatness Verification Worksheet

Internal Timebase Verification

AC Amplitude (high-impedance) Verification

Low Frequency Flatness Verification

0 dB Range Flatness Verification

+10 dB Range Flatness Verification

+20 dB Range Flatness Verification

Calibration Security

To Unsecure the Instrument Without the Security Code

Calibration Message

Calibration Count

General Calibration/Adjustment Procedure

Aborting a Calibration in Progress

Sequence of Adjustments

Self-Test

Frequency (Internal Timebase) Adjustment

Internal ADC Adjustment

Output Impedance Adjustment

AC Amplitude (high-impedance) Adjustment

Low Frequency Flatness Adjustment

0 dB Range Flatness Adjustments

+10 dB Range Flatness Adjustments

+20 dB Range Flatness Adjustment

Pulse Width (Trailing Edge Delay) Adjustment

Pulse Edge Time Adjustment

Duty Cycle Adjustment

Output Amplifier Adjustment (Optional)

Calibration Errors

Theory of Operation

Block Diagram

Main Power Supply

Power Supplies

On-Board Power Supplies

Waveform DAC and Filters

Analog Circuitry