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Agilent Technologies 54701A User's And Service Manual

2.5-ghz active probe
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User and Service Guide
Publication number 54701-97003
September 2002
For Safety and Regulatory information, see the pages behind the index.
© Copyright Agilent Technologies 1992-2002
All Rights Reserved
Agilent Technologies 54701A
2.5-GHz Active Probe

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  • Page 1 User and Service Guide Publication number 54701-97003 September 2002 For Safety and Regulatory information, see the pages behind the index. © Copyright Agilent Technologies 1992-2002 All Rights Reserved Agilent Technologies 54701A 2.5-GHz Active Probe...
  • Page 2 Agilent Technologies 54701A 2.5-GHz Active Probe The Agilent Technologies 54701A 2.5-GHz Active Probe is a probe solution for high-frequency applications.This probe is designed to be powered from a connector at the front of the oscilloscope, or with the 1143A Probe Offset Control and Power Module.
  • Page 3 Except for the probe tip, there are no field replacable parts in the Active Probe. Depending on the warranty status of your probe, if it fails it will be replaced or exchanged. See chapter 3, “Service,” for further information and how to return your probe to Agilent Technologies for service. Option 001...

  • Page 4: In This Book

    In This Book This book provides use and service documentation for the 54701A 2.5-GHz Active Probe. It is divided into three chapters. Chapter 1 shows you how to set up and operate the probe using the power connector on the oscilloscope or the separately available 1143A Probe Offset Control and Power Module.

  • Page 5: Table Of Contents

    Contents In This Book 4 1 Operating the Probe To inspect the probe 9 To connect the probe 12 Connecting the probe to the 54120 family oscilloscopes 13 Using the probe with oscilloscope power 14 Using the probe with the 1143A power module 15 Using probe accessories 16 Additional Accessories 20 2 Probing Considerations...
  • Page 6 Contents 3 Service Specifications 35 Characteristics 36 General Characteristics 37 Recommended Test Equipment 38 Service Strategy 39 To clean the instrument 40 To return the probe to for service 40 To test input resistance 42 To test dc gain accuracy 43 To test bandwidth 45 To adjust offset zero 49 Failure Symptoms 51...

  • Page 7: Operating The Probe

    Operating the Probe...
  • Page 8 Chapter 1: Operating the Probe Figure 1 11880A, Type-N(m) to Probe Adapter (not supplied, order separately) 5081-7722A, Type-N(m) to APC 3.5(f) Adapter (supplied as Option 001, or order separately) Walking-stick Ground (supplied) N(f) to BNC(m) Adapter (supplied) Included with the probe is a box of small accessories.

  • Page 9: To Inspect The Probe

    Chapter 1: Operating the Probe Introduction This chapter shows you how to connect and operate the 54701A Active Probe. The following information is covered in this chapter: • Inspection • Probe operating range • Connecting the probe • Operating the probe with oscilloscope power •...
  • Page 10 Chapter 1: Operating the Probe Probe Operating Range Probe Operating Range Figure 2 shows the maximum input voltage for the active probe as a function of frequency. This is the maximum input voltage that can be applied without risking damage to the probe. Figure 2 Maximum Input Voltage vs Frequency Figure 3 shows the operating range of the probe.
  • Page 11 Chapter 1: Operating the Probe Probe Operating Range The curves in figures 4 and 5 represent the typical input signal limits for several levels of second and third harmonic distortion in the output signal. For input signals below a given curve, the level of harmonic distortion in the output is equal to or below that represented by the curve.

  • Page 12: To Connect The Probe

    Chapter 1: Operating the Probe Probe Operating Range To connect the probe 1 Connect the probe output to the instrument input. The probe output is through a Type-N connector and the probe is designed to be terminated with 50 Ω 1%. •...

  • Page 13: Connecting The Probe To The 54120 Family Oscilloscopes

    Connecting the probe to the 54120 family oscilloscopes There are a few things to consider when connecting the 54701A Active Probe to one of the 54120 family of high performance oscilloscopes. • Use the special Type N(f) to APC 3.5(f) bulkhead adapter to connect the probe output to the input of the test set.

  • Page 14: Using The Probe With Oscilloscope Power

    The offset will be limited to a range acceptable to the probe. With 54700 family of oscilloscope plug-ins, the offset range is 50 V. See the sidebar below. • Since the 54701A is an active probe, the bandwidth of the oscilloscope and probe combination is a mathematical combination of their individual specifications.

  • Page 15: Using The Probe With The 1143A Power Module

    Chapter 1: Operating the Probe Probe Operating Range Using the probe with the 1143A power module Probe power and offset control is provided by the 1143A Probe Offset Control and Power Module. 1 Set up the power module by following the instructions in the User and Service Guide.

  • Page 16: Using Probe Accessories

    Chapter 1: Operating the Probe Probe Operating Range Using probe accessories The following figure and table illustrate the accessories supplied with the 54701A Active Probe. Figure 6 Table 1 Accessories Supplied Item Description Part Number Type-N(f) to BNC(m) adapter 1250-0077...
  • Page 17 Chapter 1: Operating the Probe Probe Operating Range Type-N to BNC Adapter The Type-N(f) to BNC(m) adapter connects the output of the probe to instruments with a BNC input. If the instrument input does not have a 50-Ω termination, use an adapter with an integral 50-Ω load or add a 50-Ω feedthrough (10100C) between the adapter and instrument input.
  • Page 18 650 MHz. Flexible Probe Adapter The flexible probe adapter provides a high-quality connection between a coaxial socket and the 54701A probe. The right-angle connection allows the probe to remain parallel to a PC board and the flexibility prevents the leverage of the probe and cable from damaging PC board circuitry.
  • Page 19 The coaxial socket is designed to fit the standard mini-probe. When used with the flexible probe adapter, it can be installed in a circuit so you can probe with the 54701A. The illustration shows the socket and the PC board layout needed to mount the socket to the board.

  • Page 20: Additional Accessories

    Chapter 1: Operating the Probe Probe Operating Range Additional Accessories The following accessories enhance use of the active probe. For ordering information, see "Replaceable Parts" in chapter 3. Type-N to APC 3.5 Adapter The Type-N(f) to APC 3.5(f) bulkhead adapter is an optional adapter (Option 001, part no.

  • Page 21: Probing Considerations

    Probing Considerations...
  • Page 22 Chapter 2: Probing Considerations Introduction This chapter gives you some guidance about the effects of probing and how to get the best measurement results. The effect of the following parameters are covered in this chapter: • Resistive Loading • Capacitive Loading •...
  • Page 23 Chapter 2: Probing Considerations Resistive Loading Effects Resistive Loading Effects The two major effects caused by resistive loading are amplitude distortion and changes in dc bias conditions in the circuit under test. Amplitude Distortion Amplitude distortion is depicted in figure 7, where waveform 1 is the signal before probing and waveform 2 is the signal while probing.
  • Page 24 Chapter 2: Probing Considerations Resistive Loading Effects Bias Changes Probes with low input resistance can cause bias changes in the device under test. A good example of this effect can be seen when probing ECL circuits. Figure 8 represents a typical ECL node with a 60-Ω bias resistor to -2 V. Ip represents current that flows from ground into the circuit when the probe is connected.

  • Page 25: Capacitive Loading Effects

    Figure 9 plots the probe impedance vs frequency for two probes: a 1-MΩ, 6-pF probe and the 54701A probe (100 kΩ, 0.6 pF). It shows that because of the lower input capacitance, the 54701A probe actually has a higher input impedance for frequencies above 240 kHz.
  • Page 26 Chapter 2: Probing Considerations Resistive Loading Effects Figure 10 represents plots from three spice simulations showing this loading effect. Plot 1 shows the signal edge before probing. Plot 2 shows the edge after probing with a 6-pF probe and plot 3 after probing with a 15-pF probe. Figure 10 Plot 1 Plot 2...

  • Page 27: Ground Inductance Effects

    Figure 11 plots the probe impedance vs frequency for two probes: a 1-MΩ, 6- pF probe and the 54701A probe (100 kΩ, 0.6 pF). It also plots the inductive reactance vs frequency for three different values of ground inductance. The 5-nH inductance represents a PC board socket, the 20-nH inductance a spanner ground, and the 100-nH inductance a 4-inch ground wire.
  • Page 28 Chapter 2: Probing Considerations Resistive Loading Effects Figure 11 1-MΩ, 6-pF probe 1-MΩ, 6-pF probe Probe Impedance and Resonance...
  • Page 29 Chapter 2: Probing Considerations Resistive Loading Effects Figure 12 shows waveforms measured by the 54701A (100 kΩ, 0.6 pf) and the 1-MΩ, 6-pF probe; both probes are connected to a 1-GHz oscilloscope. Figure 12 Waveform 1 Waveform 2 Waveform 3...
  • Page 30 Chapter 2: Probing Considerations Resistive Loading Effects The measurements from the first three waveforms lead to a rule of thumb: To minimize signal distortion due to probe resonance, provide a two-to-one, or greater, difference between the resonant frequency of the probe and the bandwidth of the signal being measured.

  • Page 31: Probe Bandwidth

    Chapter 2: Probing Considerations Resistive Loading Effects Probe Bandwidth The bandwidth of the probe is often given much consideration during purchase, then forgotten while making measurements. Error in measurements occur when the frequency content (at the -3 dB point) of the signal being measured approaches or exceeds the bandwidth of the probe.

  • Page 32: Conclusion

    5 to 10 pF, which gives a total of 10 to 20 pF. The 0.6-pF input capacitance of the 54701A probe is about 3% to 6% that of the circuit capacitance. It will not significantly change the time constant in the node being probed.

  • Page 33: Service

    Service...
  • Page 34 Chapter 3: Service Introduction This chapter provides service information for the 54701A Active Probe. The following sections are included in this chapter: • Specifications and Characteristics • Returning for Service • Calibration Testing Procedures • Making Adjustments • Troubleshooting and Repair...

  • Page 35: Specifications

    Chapter 3: Service General Information General Information The following general information applies to the 54701A 2.5 GHz Active Probe. Specifications Table 3 gives specifications used to test the active probe. Table 3 Specifications Attenuation Factor 10:1 Bandwidth (-3dB) >2.5 GH dc Gain Accuracy ±0.5%...

  • Page 36: Characteristics

    Chapter 3: Service General Information Characteristics Table 4 gives characteristics that are typical for the active probe. Table 4 Characteristics Rise time* <140 ps Input Capacitance 0.6 pF (typical) Maximum Input Voltage ±200 V[dc + peak ac(<20 MHz)] ESD Tolerance ±12 kV (150 Ω/150 pF) Flatness...

  • Page 37: General Characteristics

    Chapter 3: Service General Information General Characteristics The following general characteristics apply to the active probe. Table 5 General Characteristics Environmental Conditions Operating Non-operating Temperature 0°C to +55 C° (32°F to +131°F) -40°C to +70°C (-40°F to +158°F) Humidity up to 95% relative humidity (non- up to 90% relative humidity at condensing) at +40°C (+104°F) +65°C (+149°F)

  • Page 38: Recommended Test Equipment

    Chapter 3: Service General Information Product Regulations Safety IEC 348 UL 1244 CSA-C22.2 No.231 (Series M-89) This product meets the requirement of the European Communities (EC) EMC Directive 89/336/EEC. Emissions EN55011/CISPR 11 (ISM, Group 1, Class A equipment) SABS RAA Act No. 24 (1990) Immunity EN50082-1 Code...

  • Page 39: Service Strategy

    C = CalibrationTests, A = Adjustments, T = Troubleshooting Service Strategy The 54701A Active Probe is a high-frequency instrument with many critical relationships between parts. For example, the frequency response of the amplifier on the hybrid is trimmed to match the output coaxial cable. As a result, to return the probe to optimum performance requires factory repair.

  • Page 40: To Clean The Instrument

    To return the probe to for service Before shipping the instrument to Agilent Technologies, contact your nearest Agilent sales office for additional details. 1 Write the following information on a tag and attach it to the instrument.
  • Page 41 Chapter 3: Service Calibration Testing Procedures Calibration Testing Procedures The calibration procedures in this section are used to determine if the 54701A meets the designated warranted specifications. Testing Interval The calibration test procedures may be performed for incoming inspection of the instrument and should be performed periodically thereafter to ensure and maintain peak performance.

  • Page 42: To Test Input Resistance

    Chapter 3: Service Calibration Testing Procedures To test input resistance This test checks the input resistance of the active probe. Specification: 100 kΩ 1% Equipment Required Recommended Equipment Critical Specification Model/Part Digital Multimeter Resistance 0.1% 3458A 1 Connect the DMM between the probe tip and the ground shell at the front of the probe.

  • Page 43: To Test Dc Gain Accuracy

    Chapter 3: Service Calibration Testing Procedures To test dc gain accuracy This test checks the dc gain accuracy of the probe. Specification: 0.1 0.5% Equipment Required Recommended Equipment Critical Specification Model/Part Power Supply 5 Vdc 6114A Digital Multimeter Better than 0.1% accuracy 3458A Power Supply Power and control for probe under test...
  • Page 44 Chapter 3: Service Calibration Testing Procedures 6 Read and record the offset voltage on the DVM. _____________mV If the offset voltage is greater than 1.0 mV, continue with the test but see the second sidebar at the end of this test. 7 Connect the probe to the 5.0 V supply.

  • Page 45: To Test Bandwidth

    Chapter 3: Service Calibration Testing Procedures To test bandwidth This test checks the bandwidth of the probe. A high-frequency signal generator and two power meters are used to set the input and measure the output of the probe. Specification: down less than 3 dB, dc to 2.5 GHz Equipment Required Recommended Equipment...
  • Page 46 Chapter 3: Service Calibration Testing Procedures Figure 14 Bandwidth Test Setup 7 Adjust the signal generator power output for exactly -6.0 dBm as read on the input power meter. 8 Note the power level reading on the output power meter. 50 MHz power level _______________ dBm.
  • Page 47 Chapter 3: Service Calibration Testing Procedures Table 7 Calibration Test Record 54701A Active Probe Tested by_________________________ Serial No. ______________________________ Work Order No.____________________ Recommended Test Interval - 1 Year/2000 hours Date____________________ Recommended next testing_________________ Temperature_____________ Test Limits Results Input Resistance 100 kΩ ±1%, 99.0 kΩ to 101.0 kΩ...
  • Page 48 Chapter 3: Service Making Adjustments Making Adjustments This section provides an adjustment procedure for the 54701A Active Probe. Equipment Required Equipment required for adjustments is listed in the Recommended Test Equipment table on page 39 of this chapter. Any equipment that satisfies the critical specification listed in the table may be substituted for the recommended model.

  • Page 49: To Adjust Offset Zero

    Chapter 3: Service Making Adjustments To adjust offset zero This procedure adjusts the offset zero of the probe. Some offset in the probe can be caused by a residual offset signal from the probe's control input. Therefore, the procedure compensates for any external offset signal. Equipment Required Recommended Equipment...
  • Page 50 Chapter 3: Service Making Adjustments Use the figure below to locate the appropriate measurement points in the probe power housing. Figure 15 R13, Center J1, Pin 4 (Green Wire) Probe Power Box Adjustment Locator 9 Connect the DVM to measure the voltage between ground (the "N" connector) and the center of the adjustment pot R13.

  • Page 51: Failure Symptoms

    Chapter 3: Service Troubleshooting and Repair Troubleshooting and Repair This section provides information to determine if your probe needs adjustment or repair. • If your probe is under warranty and requires repair, returned it to. Contact your nearest Service Center. •...
  • Page 52 Chapter 3: Service Troubleshooting and Repair The frequency response of the probe is determined by the amplifier hybrid in the probe and the probe cable. If the probe fails the bandwidth test, factory repair is necessary. Also read "Incorrect Pulse Response" below. Incorrect Pulse Response (flatness) If the probe's pulse response shows a top that is not flat (incorrect ac gain), it is most likely caused by an inaccurate 50-Ω...

  • Page 53: To Prepare The Probe For Exchange

    Chapter 3: Service Troubleshooting and Repair Offset Will Not Zero With no signal input and no offset setting, the dc output of the probe should be within 1 mV. An error can be caused by several factors. • If the probe is connected to an 54700 family oscilloscope for probe power, the oscilloscope will calibrate out an offset zero error during a probe calibration.

  • Page 54: Replaceable Parts

    Replaceable Parts Except for the accessories, which includes probe tips, there are few field replaceable parts for the 54701A Active Probe. The replaceable parts are listed in table 8 below. Accessory part numbers are listed in table 1, page 16.
  • Page 55 Chapter 3: Service Troubleshooting and Repair Replaceable Parts Ref. Des. Description Part Number Foam set 5041-9442 Label, carrying case 5090-4488 Plastic parts box 1540-0022...

  • Page 56: Theory Of Operation

    Chapter 3: Service Troubleshooting and Repair Theory of Operation The following is a brief discussion of the basic operating principles of the 54701A active probe. Use the simplified circuit diagram shown below. Figure 16 Active Probe Simplified Circuit Diagram Probe Circuitry All of the probe circuitry is constructed on a ceramic substrate with discrete parts and two operational amplifier chips.
  • Page 57 Chapter 3: Service Troubleshooting and Repair High-Frequency Path The 10 signal is ac coupled to a series of discrete emitter followers, Amp 1. Operational amplifier U2 sets the bias at the input of the emitter follower amplifier. The high-frequency signal drives the emitter of a common base amplifier.
  • Page 58 Chapter 3: Service Troubleshooting and Repair...
  • Page 59 Index accessories dimensions offset 200-ohm signal lead direct mail ordering with 1143A power alligator ground Lead with oscilloscope power BNC to probe tip adapter offset errors coaxial socket offset limiting errors flexible probe adapter offset zero amplitude distortion ground extention lead adjusting bias changes nut driver...
  • Page 60 Index rule of thumb resonant frequency returning probe service strategy specifications storage environment terminating probe test equipment required test interval test record testing active probe bandwidth dc gain accuracy input resistance testing performance theory troubleshooting weight...
  • Page 61 Directive 89/336/EEC (including 93/68/EEC) and carries the CE Marking accordingly (European Union). The product was tested in a typical configuration with Agilent Technologies test systems. Date: 06/30/2000 Ken Wyatt, Product Regulations Manager For further information, please contact your local Agilent Technologies sales office, agent, or distributor...
  • Page 62 Product Regulations Safety IEC 61010-1:1990+A1:1992+A2:1995 / EN 61010-1:1993+A2:1995 This Product meets the requirement of the European Communities (EC) EMC Directive 89/336/EEC. Emissions EN55011/CISPR 11 (ISM, Group 1, Class A equipment) Immunity EN50082-1 Performance Criteria IEC 61326-1:1997+A1:1998 / EN 61326-1:1997+A1:1998 CISPR 11:1990 / EN 55011:1991 IEC 61000-4-2:1995+A1:1998 / EN 61000-4-2:1995 IEC 61000-4-3:1995 / EN 61000-4-3:1995 IEC 61000-4-4:1995 / EN 61000-4-4:1995...
  • Page 63 (for volt- age reduction or mains isola- tion), the common terminal must be connected to the earth termi- nal of the power source. Agilent Technologies P.O. Box 2197 1900 Garden of the Gods Road Colorado Springs, CO 80901-2197, U.S.A.
  • Page 64 Document Warranty WARNING The material contained in A WARNING notice this document is provided © Agilent Technologies, Inc. 2002 denotes a hazard. It calls “as is,” and is subject to No part of this manual may be attention to an operating...

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