Tektronix P7380SMA User Manual

Instruction Manual

P7380SMA
8 GHz Differential Probe

071-1392-01

Warning

The servicing instructions are for use by qualified
personnel only. To avoid personal injury, do not
perform any servicing unless you are qualified to
do so. Refer to all safety summaries prior to
performing service.

www.tektronix.com

Copyright © Tektronix, Inc. All rights reserved.

Tektronix products are covered by U.S. and foreign patents, issued and
pending. Information in this publication supercedes that in all previously
published material. Specifications and price change privileges reserved.

Tektronix, Inc., P.O. Box 500, Beaverton, OR 97077

TEKTRONIX, TEK, and TekConnect are registered trademarks of
Tektronix, Inc.

WARRANTY

Tektronix warrants that the products that it manufactures and sells will be free from defects
in materials and workmanship for a period of one (1) year from the date of shipment. If a
product proves defective during this warranty period, Tektronix, at its option, either will
repair the defective product without charge for parts and labor, or will provide a
replacement in exchange for the defective product.

In order to obtain service under this warranty, Customer must notify Tektronix of the
defect before the expiration of the warranty period and make suitable arrangements for the
performance of service. Customer shall be responsible for packaging and shipping the
defective product to the service center designated by Tektronix, with shipping charges
prepaid. Tektronix shall pay for the return of the product to Customer if the shipment is to
a location within the country in which the Tektronix service center is located. Customer
shall be responsible for paying all shipping charges, duties, taxes, and any other charges for
products returned to any other locations.

This warranty shall not apply to any defect, failure or damage caused by improper use or
improper or inadequate maintenance and care. Tektronix shall not be obligated to furnish
service under this warranty a) to repair damage resulting from attempts by personnel other
than Tektronix representatives to install, repair or service the product; b) to repair damage
resulting from improper use or connection to incompatible equipment; c) to repair any
damage or malfunction caused by the use of non-Tektronix supplies; or d) to service a
product that has been modified or integrated with other products when the effect of such
modification or integration increases the time or difficulty of servicing the product.

THIS WARRANTY IS GIVEN BY TEKTRONIX IN LIEU OF ANY OTHER
WARRANTIES, EXPRESS OR IMPLIED. TEKTRONIX AND ITS VENDORS
DISCLAIM ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE. TEKTRONIX’ RESPONSIBILITY
TO REPAIR OR REPLACE DEFECTIVE PRODUCTS IS THE SOLE AND
EXCLUSIVE REMEDY PROVIDED TO THE CUSTOMER FOR BREACH OF
THIS WARRANTY. TEKTRONIX AND ITS VENDORS WILL NOT BE LIABLE
FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES IRRESPECTIVE OF WHETHER TEKTRONIX OR THE VENDOR
HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES.

Table of Contents

Preface vii............................................

Contacting Tektronix viii.................................

General Safety Summary ix..............................

Service Safety Summary xi..............................

Getting Started 1.....................................

Probe Controls and Connections 2........................

Standard Accessorie s 6.................................

Optional Accessories 8.................................

Options 10............................................

TekConnect Interface 11.................................

Probe Inputs 12........................................

SMA Connectors 12.................................

DC Termination Voltage Control Jacks 13................

Probe Input Limitations 13............................

Probe Outputs 14......................................

Termination Voltage Monitor Jacks 14...................

Auxiliary Output SMA Connector 14....................

Functional Check 15....................................

Power-on Self Test 16................................

Signal and Termination Voltage Monitor Check 17.........

Aux Output Check 20................................

DC Termination Voltage Zero Check 22.................

Probe Calibration 24....................................

Using the Probe 26.....................................

Auto Mode 26......................................

External Mode 27...................................

Internal Mode 28....................................

Auxiliary Output 29.................................

Using the Probe With a Sampling Oscilloscope 30.........

P6150 Probe Tips 32.................................

Operating Basics 33...................................

Differential Measurements for Serial Data Compliance Testing 33

Differential Signalling 33.............................

Pseudo-Differential Measurements 34...................

Differential Probe Measurements 35....................

Common-Mode Rejection Ratio 36.....................

P7380SMA 8 GHz Differential Probe Instruction Manual

i

Table of Contents

Probe Block Diagram (Simplified) 37......................

Matched-Delay Cables 37.............................

Input Termination Network 38.........................

Internal Probe Amplifier 40...........................

Termination Voltage Control 44...........................

Auto Mode 45......................................

Int Mode 45........................................

Ext Mode 45.......................................

Overdrive Error 4 7.....................................

Differential and Single-Ended Signal Measurement 48.........

Differential Measurement Topology 48..................

Differential Dynamic Range 49........................

Single-Ended Measurement Topology 50.................

Single-Ended Measurement Procedure 54................

Single-Ended Dynamic Range 55.......................

Extending the Input Connections 56.......................

Checking Cable Skew 57................................

Adjusting Cable Skew 58................................

Deskewing Probes 60...................................

Reference 63.........................................

Serial Bus Standards 63.................................

InfiniBand 64.........................................

ii

P7380SMA 8 GHz Differential Probe Instruction Manual

Table of Contents

Appendix A: Specifications 65...........................

Warranted Characteristics 65.............................

Typical Characteristics 66...............................

Nominal Characteristics 71..............................

Mechanical Characteristics 71............................

Appendix B: Performance Verification 73.................

Equipment Required 73.................................

Special Adapters Required 75............................

TekConnect-to-SMA Adapter 75.......................

Equipment Setup 76....................................

Input Resistance 77.....................................

Termination Voltage Accuracy 78.........................

Ext Mode 78.......................................

Int Mode 79........................................

Auto Mode 80......................................

Output Offset Zero 82...................................

DC Gain Accuracy 83...................................

Gain Check at 2.5X Attenuation 83.....................

Gain Check at 12.5X Attenuation 85....................

Rise Time 85..........................................

Rise Time Check at 12.5X Attenuation 85................

Rise Time Check at 2.5X Attenuation 89.................

Appendix C: User Service 91............................

Probe/Adapter/Oscilloscope Compatibility 91................

Check Compatibility 91..............................

Error Conditions 92....................................

Inspection and Cleaning 93..............................

Replacement Parts 93...................................

Preparation for Shipment 94..............................

P7380SMA 8 GHz Differential Probe Instruction Manual

iii

Table of Contents

List of Tables

Table 1: P7380SMA features 2..........................

Table 2: P7380SMA standard accessories 6................

Table 3: Optional accessories 8..........................

Table 4: Equipment required for functional checks 15.........

Table 5: Common-mode voltage and current table 39.........

Table 6: Differential to single-ended conversion table 55......

Table 7: Serial bus standards with

dynamic range requirements 63........................

Table 8: Warranted electrical characteristics 65..............

Table 9: Typical electrical characteristics 66................

Table 10: Nominal electrical characteristics 71..............

Table 11: Typical mechanical characteristics 71..............

Table 12: Equipment required for performance verification 73..

Table 13: P7380SMA probe compatibiity issues 91...........

Table 14: LED error conditions 92........................

iv

P7380SMA 8 GHz Differential Probe Instruction Manual

List of Figures

Figure 1: P7380SMA differential probe 1..................

Figure 2: Connecting and disconnecting the probe 11..........

Figure 3: Probe signal input connections 12.................

Figure 4: Signal check setup 17...........................

Figure 5: Aux output check test setup 20....................

Figure 6: DC termination voltage check setup 22.............

Figure 7: Probe calibration setup 25........................

Figure 8: Using Auto Termination Voltage Control Mode 26....

Figure 9: Using External Termination Voltage Control Mode 27.
Figure 10: Using Internal Termination Voltage Control Mode 28.
Figure 11: Viewing the Aux Out signal on a spectrum analyzer 29
Figure 12: Using the probe with an 80A03 Interface and an 80A05

Module to view eye diagrams on a TDS8000 Series sampling

oscilloscope 31.....................................

Figure 13: P6150 probe tips 32............................

Figure 14: Simplified model of a differential amplifier 36......

Figure 15: Input termination network 37....................

Figure 16: Probe maximum input limits 42..................

Figure 17: Differential and Common-Mode operating ranges 43.

Figure 18: Termination voltage network drive 44.............

Figure 19: Overdrive Error indicator 47.....................

Figure 20: Differential measurement topology 48.............

Figure 21: 50 ohm termination on (--) input 51...............

Figure 22: Shorting termination on (--) input 52..............

Figure 23: Open (--) input 53.............................

Figure 24: Checking skew between inputs 57................

Figure 25: Using the phase adjuster 59.....................

Figure 26: Deskewing two P7380SMA probes 61.............

Figure 27: InfiniBand signals 64..........................

Figure 28: Typical CMRR plot 68.........................

Figure 29: Typical differential input return loss 69............

Figure 30: Typical differential-mode bandwidth 69............

Figure 31: Typical eye pattern from an InfiniBand signal 70....

Figure 32: Typical differential step response 70..............

Figure 33: Probe dimensions 72...........................

Figure 34: TekConnect-to-SMA Adapter 75.................

Figure 35: Preliminary test setup 76........................

Table of Contents

P7380SMA 8 GHz Differential Probe Instruction Manual

v

Table of Contents

Figure 36: Checking differential mode input resistance 77......

Figure 37: Termination Voltage Accuracy, Ext mode setup 78...
Figure 38: Termination Voltage Accuracy, Auto mode setup 80..

Figure 39: Setup for the output offset zero test 82.............

Figure 40: DC Gain Accura cy setup 83.....................

Figure 41: Reverse the power supply polarity

on the probe inputs 84................................

Figure 42: Test system rise time setup 86...................

Figure 43: Setting the TDR parameters 87...................

Figure 44: Test system rise time setup with probe 88..........

vi

P7380SMA 8 GHz Differential Probe Instruction Manual

Preface

This is the Instruction Manual for the P7380SMA differential probe.
This manual provides operating information, specifications, and
performance verification procedures for the probe.

P7380SMA 8 GHz Differential Probe Instruction Manual

vii

Preface

Contacting Tektronix

Phone [phone]*

Address Tektronix, Inc.

Department or name (if known)
14200 SW Karl Braun Drive
P.O. Box 500
Beaverton, OR 97077
USA

Web site www.tektronix.com

Sales

1-800-833-9200, select option 1*

support

Service

1-800-833-9200, select option 2*

support

Technical

www.tektronix.com/support

support

1-800-833-9200, select option 3*

6:00 a.m. -- 5:00 p.m. Pacific Standard Time

* This phone number is toll free in North America. After office hours, please

leave a voice mail message.
Outside North America, contact a Tektronix sales office or distributor; see
the Tektronix web site for a list of offices.

viii

P7380SMA 8 GHz Differential Probe Instruction Manual

General Safety Summary

Review the following safety precautions to avoid injury and prevent
damage to this product or any products connected to it. To avoid
potential hazards, use this product only as specified.

To Avoid Fire or Personal Injury

Connect and Disconnect Properly. Connect the probe output to the

measurement instrument before connecting the probe to the circuit
under test. Disconnect the probe input from the circuit under test
before disconnecting the probe from the measurement instrument.

Observe All Terminal Ratings. To avoid fire or shock hazard, observe all

ratings and markings on the product. Consult the product manual for
further ratings information before making connections to the product.

The common terminal is at ground potential. Do not connect the
common terminal to elevated voltages.

Do Not Operate Without Covers. Do not operate this product with

covers or panels removed.

Do Not Operate With Suspected Failures. If you suspect there is damage

to this product, have it inspected by qualified service personnel.

Do Not Operate in Wet/Damp Conditions.

Do Not Operate in an Explosive Atmosphere.

Keep Product Surfaces Clean and Dry.

P7380SMA 8 GHz Differential Probe Instruction Manual

ix

General Safety Summary

Safety Terms and Symbols

Terms in This Manual. These terms may appear in this manual:

WARNING. Warning statements identify conditions or practices that
could result in injury or loss of life.

CAUTION. Caution statements identify conditions or practices that
could result in damage to this product or other property.

Terms on the Product. These terms may appear on the product:

DANGER indicates an injury hazard immediately accessible as you
read the marking.

WARNING indicates an injury hazard not immediately accessible as
you read the marking.

CAUTION indicates a hazard to property including the product.

Symbols on the Product. These symbols may appear on the product:

CAUTION

Refer to Manual

x

P7380SMA 8 GHz Differential Probe Instruction Manual

Service Safety Sum mary

Only qualified personnel should perform service procedures. Read
this Service Safety Summary and the General Safety Summary before
performing any service procedures.

Do Not Service Alone. Do not perform internal service or adjustments

of this product unless another person capable of rendering first aid
and resuscitation is present.

P7380SMA 8 GHz Differential Probe Instruction Manual

xi

Service Safety Summary

xii

P7380SMA 8 GHz Differential Probe Instruction Manual

Getting Started

The P7380SMA is an 8 GHz, active differential probe designed for
Serial Data Analysis (SDA) compliance testing and other applica­tions that use differential serial busses in a 50 Ω signaling environ-
ment. The SMA input connectors each terminate with an internal
50 Ω resistor. The internal 50 Ω resistors are not dire ctly grounded,
but are driven by a buffer amplifier to a common-mode DC
termination voltage. The termination voltage range allows the
termination voltage to be set to any value within the specified
common mode voltage range of the input signal.

The DC termination voltage can be supplied either externally or
internally, including an automatic mode that sets the value of the
termination voltage to match the input signal DC common-mode
voltage. The P7380SMA probe has two selectable attenuator settings
that provide a tradeoff between dynamic range and noise. The
P7380SMA probe has been optimized for a clean pulse response for
accurate SDA compliance testing.

Figure 1: P7380SMA differential probe

P7380SMA 8 GHz Differential Probe Instruction Manual

1

Getting Started

The probe incorporates the high-performance TekConnect interfa ce
to communicate with the host instrument. In addition to the acquired
signal that is routed through the TekConnect interface, the probe also
provides a full-bandwidth, inverted-phase auxiliary output. The
auxiliary output can be used for additional signal analysis by
connecting it to a spectrum analyzer, network analyzer, or clock
recovery unit.

The probe is shipped with 50 Ω termination caps connected to the
three SMA input and output connectors. When you are not using the
probe, leave the termination caps connected to protect the circuitry
from damage.

Always leave the Auxiliary output connector terminated when not in
use, to provide the best signal fidelity for the main probe output.

Probe Controls and Connections

Table 1 briefly outlines the controls and c onnections of the
P7380SMA differential probe. Additional information can be found
later in Getting Started and the following Operating Basics sections.

Table 1: P7380SMA features

Control/Connection Description

TekConnect interface. The TekConnect interface provides a

communication path between the probe and the oscilloscope.
Contact pins provide power, signal, offset, and probe characteris­tic data transfer.

The probe snaps into the oscilloscope when fully engaged. To
remove, grasp the compensation box, press the latch button, and
pull the probe out.

For more information, see page 11.

2

P7380SMA 8 GHz Differential Probe Instruction Manual

Table 1: P7380SMA features (Cont.)

Control/Connection Description

Input signal connections. The SMA terminals provide shielded,

low-noise connections to your circuit. Differential or single-ended
signals are buffered by the internal probe amplifier and are sent
through the TekConnect interface to the oscilloscope.

See Probe Inputs on page 12 for more information.

External DC termination control voltage connections. The red
and black 0.080 in jacks on the end of the probe provide a means
for controlling the DC termination voltage with an external DC
power supply.

Getting Started

You should use the Banana-to-0.080 in plug adapter cables
included with the probe when connecting external control voltages
to these terminals.

The Overdrive Error LED glows continually red when the
termination voltage driver current exceeds its linear range.
In general, this will occur when the termination voltage differs from
the common-mode voltage by about 2.0 volts for zero-ohm source
impedances and about 4.0 volts for 50 ohm source impedances.

The Overdrive Error LED flashes when the termination voltage in
Auto Mode or EXT Mode exceeds the specified ±2.5 volt range by
about 10%.

The Overdrive Error LED clears when the range violation signal is
removed.

For more information, see pages 13 and 47.

P7380SMA 8 GHz Differential Probe Instruction Manual

3

Getting Started

Table 1: P7380SMA features (Cont.)

Control/Connection Description

Attenuation/Dynamic Range Select and indicators. The Atten

Dynamic Range Select button allows you to select between 2.5X
and 12.5X probe attenuation settings. Note that the maximum
linear dynamic range for each attenuator setting is specified as a
differential peak-to-peak value.

The two indicator LEDs light briefly when the probe is powered
on, and then the 12.5X LED lights to indicate the 12.5X
attenuation is selected.

If both LEDs flash, an internal probe diagnostic fault exists.
Disconnect and reconnect the probe to restart the power-on
diagnostic sequence. If the LEDs continue to flash, the probe is
defective, and must be returned to Tektronix for repair.

1

Termination Voltage Control Mode Select and indicators.

The V Term Source Select button allows you to select between
three termination voltage control modes—Auto, Internal, and
External. The three indicator LEDs light briefly when the probe is
powered on, and then the Auto LED lights.

1

The probe initially sets to Auto mode; press the SELECT button to
choose another mode. The Auto Mode LED also flashes when the
probe signal inputs are AC-coupled or open-circuit. When this
happens, the termination voltage is set to 0.0 V.

In Auto mode, the input signal DC common mode voltage is
measured and the DC termination voltage is automatically set to
equal that voltage. This is the default mode setting when the
probe is powered on.

In Internal mode, the DC termination voltage is set with user
interface controls that are available on TekConnect-interface
oscilloscopes that support this mode. If your oscilloscope does not
support this mode, the termination voltage defaults to 0 volts.

In External mode, the DC termination voltage is controlled
indirectly with an external DC power supply connected to the

0.080 in pin jacks on the probe face plate. If these control voltage
inputs are left open, the termination voltage defaults to 0 volts.

4

P7380SMA 8 GHz Differential Probe Instruction Manual

Table 1: P7380SMA features (Cont.)

Control/Connection Description

Termination Voltage Monitor jacks. These red and black jacks

provide a means for connecting a DMM to the probe to monitor
the DC termination voltage. For example, this can be used in Auto
mode to indirectly measure the DC common-mode input voltage.

Auxiliary Output connector. This SMA connector provides a
full-bandwidth, attenuated, inverted sample of the input signal.
Use this auxiliary signal to trigger your TDS/CSA 8000 series
sampling oscilloscope, or as an input to a spectrum analyzer or
network analyzer to measure the frequency domain response of
the input signal.

Getting Started

When you are not using this connector, leave the termination cap
connected to protect the SMA output connector from damage and
to ensure maximum signal fidelity of the main probe output signal
to the oscilloscope.

1

If the Attenuation and Termination Source LEDs do not light as described,
the host oscilloscope may have stored different attenuation and termination
source settings from a previous session. Use the SELECT buttons on the
probe to change the settings if necessary.

P7380SMA 8 GHz Differential Probe Instruction Manual

5

Getting Started

Standard Accessories

Table 2 shows the standard accessories included with the P7380SMA
differential probe. To order replacements, use the Tektronix part
number listed with each accessory.

Table 2: P7380SMA standard accessories

Accessory Description

Carrying case with inserts. The soft-sided nyloncarrying casehas

several compartments to hold the probe, accessories, and related
documentation. Use the case to store or transport the probe.

Tektronix part number 016-1952-XX

Male SMA 50 Ω termination (3 ea). The probe is shipped with
these terminations connected to the probe SMA inputs and the
Auxiliary Output connector. Protect the probe circuitry by
connecting the terminations to these connectors when the probe
is not in use.

When making single-ended measurements in a 50 Ω
environment, one of these terminations may be used on the
unused input.

Only remove the 50 Ω termination from the Auxiliary Output
connector when you connect the Auxiliary Output to another
measurement instrument, such as a network analyzer. Otherwise,
leave the termination connected to the probe.

Tektronix part number: 015-1022-XX (package of 1)

Male SMA short-circuit. Use this adapter when performing a
functional check on the probe.

The SMA short-circuit may also be used to terminate an unused
input in one possible single-ended measurement topology.
See page 52 for more information.

Tektronix part number: 015-1020-XX

6

P7380SMA 8 GHz Differential Probe Instruction Manual

Table 2: P7380SMA standard accessories (Cont.)

Accessory Description

SMA Female-to-BNC Male adapter. Use the adapter to connect

the probe SMA inputs to BNC connections, such as the BNC
calibration output connector on your oscilloscope.

Tektronix part number: 015-0572-XX

Dual SMA cables. These 38 in cables are bound together and
have factory-calibrated integral phase adjusters to limit
cable-to-cable skew to less than 1 ps. (See page 8 for external,
user-adjustable phase adjusters.) The cables are color-coded at
each end for easy identification, and provide matched signal paths
from your circuit to the probe to ensure accurate differential signal
measurements. The P7380SMA differential probe includes built-in
cable loss compensation when used with the cable assembly.

Getting Started

Note: To make DUT connections easier, connect the phase­adjuster ends of the cables to the probe inputs.

Tektronix part number: 174-4944-XX

0.080 in Pin-to-Banana plug adapter cables. Use these cables
in external mode to control the DC termination voltage, using an
external power supply to set the value.

Tektronix part number: 012-1674-XX (red), 012-1675-XX (black)

0.040 in-to-0.080 in Pin jack adapters. Use two pin jack
adapters to connect the 0.040 in Termination Voltage Monitor
jacks to the 0.080 in pin-to-banana plug adapter cables. Connect
the banana plug ends of the cables to a DMM to measure the
termination voltage.

Tektronix part number: 012-1676-XX (package of 1)

Antistatic wrist strap. When using the probe, always work at an
antistatic work station and wear the antistatic wrist strap.

Tektronix part number: 006-3415-XX

P7380SMA 8 GHz Differential Probe Instruction Manual

7

Getting Started

Table 2: P7380SMA standard accessories (Cont.)

Accessory Description

Calibration certificate. A certificate of traceable calibration is

provided with every instrument shipped.

Instruction Manual. Provides instructions for operating and
maintaining the P7380SMA differential probe.

Tektronix part number: 071-1392-XX

Optional Accessories

Table 3 shows the optional accessories that you can order for the
P7380SMA differential probe.

Table 3: Optional accessories

Accessory Description

Phase adjuster. Use two phase adjusters if you need to bring the

skew between inputs to 1 ps or less because of skew in the
device under test differential signal path. See Adjusting Cable
Skew on page 58 for instructions. The phase adjuster has a 25 ps
adjustment range.

The matched-delay SMA cables that come with your probe have a
≤1 ps skew at the cable ends.

Tektronix part number: 015-0708-XX (package of 1)

8

P7380SMA 8 GHz Differential Probe Instruction Manual

Table 3: Optional accessories (Cont.)

Accessory Description

80A03. The 80A03 TekConnect Probe Interface Module is an

80A03

adapter that allows you to use TekConnect probes with CSA8000
and TDS8000 Series sampling oscilloscopes and 80E0X sampling
modules.

The interface is comprised of an enclosure that houses a
compartment for one 80E0X electrical sampling module and two
TekConnect probe inputs. The interface routes the probe signal
outputs through SMA connectors on the front panel. Semi-rigid
SMA cables link the probe outputs to the 80E0X module inputs.

The 80A03 Interface Module is required to complete a
performance verification of the probe.

Getting Started

P6150 Probe. Use the P6150 probe for checking discrete test
points in your circuit. An assortment of circuit and grounding
attachments are included to help you maintain high signal
integrity.

For best high-frequency performance, the wide-blade ground
accessory should be used with the probe tips and cut as short as
possible to connect to a ground point near the probed signal.
However, to prevent delay mismatches, do not use the cable
included with the P6150 probe. Instead, attach the tips to the ends
of the matched SMA cables that are included with the P7380SMA
probe.

Note: The P6150 probe includes (one) 1X- and (two) 10X­attenuation probe tips. If you need more tips, see P6150
Attenuation Tips below for ordering information.

P6150 Attenuator Tips. These tips attach to the ends of the
matched SMA cables that are included with the P7380SMA
probe, and are available in 1X and 10X attenuation values.

Tektronix part number: 206-0398-00 (1X Attenuation, 1 each)

Tektronix part number: 206-0399-03 (10X Attenuation, pkg of 2)

P7380SMA 8 GHz Differential Probe Instruction Manual

9

Getting Started

Options

These options are available when ordering the P7380SMA probe:

H Option D1--Calibration Data Report

H Option D3--Calibration Data Report, 3 years (with Option C3)

H Option C3--Calibration Service 3 years

H Option D5--Calibration Data Report, 5 years (with Option C5)

H Option C5--Calibration Service 5 years

H Option R3--Repair Service 3 years

H Option R5--Repair Service 5 years

10

P7380SMA 8 GHz Differential Probe Instruction Manual

TekConnect Interface

The P7380SMA probe is powered through a TekConnect interface
between the probe compensation box and the host instrument. The
TekConnect interface provides a communication path through
contact pins on the host instrument. Power, signal, offset, and probe
characteristic data transfer through the interface.

When the probe is connected, the host instrument reads EEPROM
information from the probe, identifying the device and allowing the
appropriate power supplies to be turned on. The preamp inputs on the
host instrument are ESD protected by remaining grounded until a
valid TekConnect device is detected.

The TekConnect interface features a spring-loaded latch t hat
provides audible and tactile confirmation that a reliable connection
has been made to the host instrument. Slide the probe into the
TekConnect receptacle on the host instrument. The probe snaps into
the receptacle when fully engaged. See Figure 2.

Getting Started

To release the probe from the host instrument, grasp the compensa­tion box, press the latch button, and pull out the probe.

Latch button

Figure 2: Connecting and disconnecting the probe

P7380SMA 8 GHz Differential Probe Instruction Manual

11

Getting Started

Probe Inputs

The P7380SMA probe has two pairs of input connectors—one for
SMA signals and one for external DC termination voltages. Options
for the SMA input connections are shown in Figure 3.

Dual SMA cables

50 Ω

Terminations

Figure 3: Probe signal input connections

SMA Connectors

The SMA connectors provide a signal path through the internal 50 Ω
termination network and differential probe buffer amplifier to the
oscilloscope.

Use the matched-delay SMA cables that are supplied with the probe
to connect the probe to your circuit.

12

Leave the 50 Ω terminations on the unused inputs.

P7380SMA 8 GHz Differential Probe Instruction Manual

Getting Started

DC Termination Voltage Control Jacks

Jacks are provided on the probe faceplate for external control of the
DC termination voltage, when the Vterm Source Select is set to EXT
mode. The jacks accept the 0.080 in pin-to-banana cables included
with your probe, to connect to an external power supply with banana
plug outputs.

The red terminal is the DC control voltage input to a buffer amplifier
that drives the center-tap (common-mode node) of the internal 50 Ω
termination network. The 100 KΩ resistance to ground at the buffer
amplifier input gives a 0.00V termination voltage in EXT mode with
the inputs open. The black terminal is connected to system ground.

The normal termination voltage range is ±2.5 volts. The buffer
amplifier input is diode-protected to ±15 volts, but the Overdrive
Error LED will flash when the EXT termination voltage is driven
about 10% beyond the specified ±2.5 V range. See Overdrive Error
on page 47 for more information.

Probe Input Limitations

Although the allowable input DC common mode (V
the termination voltage (V

) range are both ±2.5 V, there are

T

additional limitations on the voltage difference between V

) range and

CM

CM

and V

that you must consider, to avoid non-linear operation.

Because of the low resistance 50 Ω termination network, relatively
large currents can flow, depending on the input signal source
impedance and the V
amplifier that drives the V

and VTvoltage difference. Since the

CM

voltage node between the two 50 Ω

T

termination resistors (see Figure 15 on page 37) has a current limit of
about ±82 mA for linear operation, this limits the allowable voltage
difference between V

As a general guideline, the voltage difference between V

CM

and VT.

CM

and V

T

should be limited to about 2 V for zero-ohm source impedances and
about 4 V for 50-ohm source impedances. More exact calculations of
the termination network and input load currents can be made using
the equations in Table 5 on page 39.

T

P7380SMA 8 GHz Differential Probe Instruction Manual

13

Getting Started

Probe Outputs

The probe provides terminals for monitoring the DC termination
voltage of the measured signal. Also, the inverted polarity of the
output signal that is passed through the TekConnect interface to the
oscilloscope is brought out to an SMA connector. These connections
are located on the top panel of the probe.

Termination Voltage Monitor Jacks

Two 0.040 in jacks allow you to monitor the termination voltage of
the signal under test, using a DMM and a pair of standard DMM test
leads. The output impedance of the termination voltage monitor (+)
output is about 1K ohm. The other output of the termination voltage
monitor is connected to signal ground.

Auxiliary Output SMA Connector

This SMA connector provides an attenuated, inverted sample of the
signal under test. The attenuation factor of the output signal m atches
the selected attenuation factor of the probe. This signal c an be used
to trigger your TDS/CSA 8000 series sampling oscilloscope, or as an
input to a spectrum- or network analyzer.

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P7380SMA 8 GHz Differential Probe Instruction Manual