Agilent 3A USER Datasheet

User’s Guide

Publication number 54753-97015 Third edition, May 2000

For Safety information, Warranties, and Regulatory information, see pages behind the index

Agilent 54753A and 54754A TDR Plug-in Modules

Agilent 54753A and 54754A Plug-in Modules

The Agilent 54753A and 54754A TDR plug-in modules provide you with TDR and TDT measurement features. In addition to the TDR and TDT measurement features, the TDR plug-ins provide two accurate oscilloscope measurement channels with user selectable bandwidths of

12.4 or 18 GHz. The lower bandwidth mode provides excellent oscilloscope noise performance for accurate measurement of small signals. The high bandwidth mode provides high-fidelity display and measurement of very high-speed waveforms.

The Agilent 54753A TDR plug-in module provides:

• Automatic and manual single-ended TDR and TDT measurement capability

• Automatic and manual waveform, histogram, FFT, waveform math, eye pattern measurements, statistical measurements, and limit testing capabilities.

• User selectable 12.4 or 18 GHz bandwidth (Channel 1).

• User selectable 12.4 or 20 GHz bandwidth (Channel 2).

• 2.5 GHz bandwidth trigger channel.

• 3.5 mm (m) connectors.

The Agilent 54754A TDR plug-in module provides:

• Automatic and manual single-ended and differential TDR and TDT measurement capability.

• Automatic and manual waveform, histogram, FFT, waveform math, eye pattern measurements, statistical measurements, and limit testing capabilities.

• User selectable 12.4 or 18 GHz bandwidth.

• 2.5 GHz bandwidth trigger channel.

• 3.5 mm (m) connectors.

ii

Accessories Supplied

The following accessories are supplied with the TDR plug-in modules:

One 50 ohm SMA (m) terminator, Agilent part number 1250-2153

Two SMA shorts (m), Agilent part number 0960-0055

TDR Demo Board, Agilent part number 54754-66503

One User’s Guide

One Programmer’s Guide

One Service Guide

Accessories Available

The following accessories are available for use with the TDR plug-in modules.

Options

Option 0B1 Additional set of user documentation

Option 001 Agilent 83480A mainframe operating system upgrade

Option 002 Agilent 54750A mainframe operating system upgrade

Option 003 Delete demo board

Agilent 54755A TDR option for Agilent 83480A mainframe operating system upgrade

Optional Accessories

Agilent 10086A ECL terminator

Agilent 54006A 6 GHz divider probe

Agilent 54007A accessory kit

Agilent 54008A 22 ns delay line

Agilent 54118A 500 MHz to 18 GHz trigger

Agilent 54701A 2.5 GHz Active Probe with Option 001

Connection Devices

SMA (f-f) adapter, Agilent part number 1250-1158

APC 3.5 (f-f) adapter, Agilent part number 1250-1749

iii

In This Book

This book is the operating manual for the Agilent 54753A and 54754A TDR plugin modules, and contains 13 chapters.

General Information Chapter 1 contains overview information, menu and front panel key information, and trigger information. Chapter 2 contains important information on the care of the TDR plug-in connectors.

TDR Front Panel and Menu Keys Chapter 3, 4, 5 and 6 describe the front panel keys and all the menu keys.

Task Oriented Examples Chapter 7 contains example single-ended TDR measurements using a demo board included with each TDR plug-in module. Chapter 8 contains example differential TDR measurements.

TDR Theory Chapters 9, 10, and 11 contain in-depth theory of TDR transmission lines and how to use TDR in designing systems.

Specifications and Characteristics Chapter 12 contains the specifications and characteristic for the TDR plug-in modules.

Problems and Error Messages Chapter 13 contains troubleshooting information and error messages.

iv

Displaying the TDR/TDT Setup Menu 5-7 Stimulus 5-7 TDT 1 dest 5-8 Normalize response . . . 5-8 TDR rate automatic . . . (250 kHz) 5-11 Preset TDR/TDT 5-12 TDT 2 dest 5-13 Normalize response . . . 5-13 TDR rate automatic . . . (250 kHz) 5-16 Preset TDR/TDT 5-17 TDT 1 dest 5-18 TDT 2 dest 5-18 Normalize 1 response . . . Normalize 2 response . . . 5-19

Contents-2

TDR rate automatic . . . (250 kHz) 5-21 Preset TDR/TDT 5-22 TDR/TDT 5-23 TDR response 1 5-23 TDR response 2 5-24 TDT response 1 5-25 TDT response 2 5-25 Establish ref plane 5-26 TDR rate automatic . . . (250 kHz) 5-27 Preset TDR/TDT 5-28 TDT 1 dest 5-30 TDR 1 dest 5-30 Normalize response . . . 5-31 TDR rate automatic . . . (250 kHz) 5-34 Preset TDR/TDT 5-34

Contents

Measure and Other TDR Specific Menus 6-1

TDR/TDT Measure Menu 6-4 Marker Menu 6-9 Reference 6-9 Marker units . . . 6-9 Response Menu Items 6-10

Single-ended TDR Measurements 7-1

Single-ended TDR Features 7-3 Establishing the Reference Plane and Normalizing 7-8 Measuring Transmission Line Impedance 7-19 Measuring Transmission Line Percent Reflection 7-25

Contents-3

Contents

Measuring Excess L/C 7-32 Measuring the Distance to a Discontinuity 7-37

Differential TDR Measurements 8-1

Differential TDR Features 8-3 Measuring Differential and Common Mode Impedance 8-5 Making Differential TDT Measurements 8-15

TDR Fundamentals 9-1

Propagation on a Transmission Line 9-4 Step Reflection Testing 9-6 Instrument Configuration 9-23

Improving Time Domain Network Measurements 10-1

Sources of Measurement Error 10-3 Removing Measurement Errors 10-6

Transmission Line Theory Applied to Digital Systems 11-1

Transmission Line Design 11-2 Signal Propagation Delay for Microstrip and Strip Lines with Distributed or Lumped Loads 11-15 Microstrip Transmission Line Techniques Evaluated Using TDR Measurements 11-21 References 11-38

Contents-4

Specifications and Characteristics 12-1

Specifications 12-3 Vertical Specifications 12-4 Environmental Specifications 12-5 Power Requirements 12-7 Weight 12-7 Characteristics 12-7 Trigger Input Characteristics 12-7 Product Regulations 12-8

In Case of Difficulty 13-1

Contents

If You Have Problems 13-3 If the Mainframe Does Not Operate 13-3 If the Plug-in Does Not Operate 13-4 Error Messages 13-5

Contents-5

Contents

Contents-6

1

The Instrument at a Glance

Operating the Instrument

What you’ll find in this chapter

This chapter describes:

• the key conventions used in this manual

• the front panel, rear panel and keys that do not display menus on the screen

Understanding the information in this chapter will help you successfully operate the instrument.

CAUTION

The input circuits can be damaged by electrostatic discharge (ESD). Therefore, avoid applying static discharges to the front-panel input connectors. Before connecting any coaxial cable to the connectors, momentarily short the center and outer conductors of the cable together. Avoid touching the front-panel input connectors without first touching the frame of the instrument. Be sure the instrument is properly earth-grounded to prevent buildup of static charge.

1-2

The Instrument at a Glance

Menu and Key Conventions

The keys labeled Trigger, Disk, and Run are all examples of front-panel keys. Pressing some front-panel keys accesses menus of functions that are displayed along the right side of the display screen. These menus are called softkey menus.

Softkey menus list functions other than those accessed directly by the frontpanel keys. To activate a function on the softkey menu, press the unlabeled key immediately next to the annotation on the screen. The unlabeled keys next to the annotation on the display are called softkeys.

Additional functions are listed in blue type above and below some of the frontpanel keys. These functions are called shifted functions. To activate a shifted function, press the blue front-panel Shift key and the front-panel key next to the desired function.

Throughout this manual front-panel keys are indicated by bold lettering of the key label, for example, Time base. Softkeys are indicated by italic lettering of the key label, for example, Scale. The softkeys displayed depend on the front- panel key pressed and which menu is selected. Shifted functions are indicated by the front-panel Shift key followed by the shaded shifted function, for example the Local function (above the Stop/Single front-panel key) will be shown as Shift, Local.

A softkey with On and Off in its label can be used to turn the softkey’s function on or off. To turn the function on, press the softkey so On is highlighted. To turn the function off, press the softkey so Off is highlighted. An On or Off softkey function will be indicated throughout this manual as: Te st On

A softkey such as Sweep Triggered Freerun offers you a choice of functions. In this case you could choose Triggered by pressing the softkey until Triggered is highlighted, or choose Freerun by pressing the softkey until Freerun is highlighted. Softkey choices will be indicated throughout this manual as: Sweep Triggered Freerun Triggered

When some softkeys, such as Calibrate Probe, are pressed the first time, a calibration will be made. Some softkeys, such as Offset require the entry of a numeric value. To enter or change the value, use the general purpose knob located below the front-panel Measure section.

.

1-3

The Instrument at a Glance

The Agilent 54753A, 54754A TDR Plug-In Modules

The TDR plug-in modules are two of several plug-in modules available for the Agilent 83480A and Agilent 54750A mainframes.

Plug-in Module Purpose

The purpose of the plug-in module is to provide measurement channels, including sampling, for the mainframe. The plug-in module scales the input signal, sets the bandwidth of the system, and allows the offset to be adjusted so the signal can be viewed. The output of the plug-in module is an analog signal that is applied to the ADCs on the acquisition boards inside the mainframe. The plug-in module also provides a trigger signal input to the time base/trigger board inside the mainframe.

Front Panel of the Plug-in Module

The plug-in module takes up two, of the four, mainframe slots. The front panel of the plug-in module has two channel inputs and an external trigger input. The front panel also has two probe power connectors for Agilent 54700-series probes, an auxiliary power connector for general purpose use, and a key for each channel that displays the softkey menu. The softkey menu allows you to access the channel setup features of the plug-in module for the selected input.

1-4

Figure 1-1

The Instrument at a Glance

Getting the Best Performance

Front panel of the plug-in module.

Getting the Best Performance

To ensure you obtain the specified accuracy, you must perform a plug-in module vertical calibration. The calibration must also be performed when you move a plug-in module from one slot to another or to a different mainframe. Refer to

“Performing a Plug-in Module Vertical Calibration” on page 3-12 for information

on performing a plug-in module vertical calibration.

1-5

The Instrument at a Glance

Installing a Plug-in Module

You do not need to turn off the mainframe to install or remove a plug-in module. The plug-in module can be installed in slots 1 and 2 or 3 and 4 on the Agilent 83480A, 54750A mainframe. The plug-in module will not function if it is installed in slots 2 and 3.

To make sure the instrument meets all of the published specifications, there must be a good ground connection from the plug-in module to the mainframe. The RF connectors on the rear of the plug-in module are spring loaded, so fingertighten the knurled screw on the front panel of the plug-in module to make sure the plug-in is securely seated in the mainframe.

CAUTION

Do not use extender cables to operate the plug-in module outside of the mainframe. The plug-in module and/or mainframe can be damaged by improper grounding when using extender cables.

Trigger

The external trigger level range for this plug-in module is ±1 V. The trigger source selection follows the slots the plug-in module is installed in. For example, if the plug-in module is installed in slots 1 and 2, then the trigger source is listed as trigger 2. If it is installed in slots 3 and 4, then the trigger source is listed as trigger 4.

The maximum safe input voltage is ±2 V + peak ac (+16 dBm). Therefore, to

!

avoid damaging the trigger input circuitry, do not apply any voltage outside this range.

The input circuits can be damaged by electrostatic discharge (ESD). Therefore, avoid app lying static discharges to the front-panel i nput connectors. Before connecting any coaxial cable to the connectors, momentarily short the center and outer conductors of the cable together. Avoid touching the frontpanel input connectors without first touching the frame of the instrument. Be sure the instrument is properly earth-grounded to prevent buildup of static charge.

1-6

2

Care and Handling of Precision Connectors

The Care and Handling of Precision Connectors

What you’ll find in this chapter

This chapter describes:

• 3.5 mm connector care

• connector wear

• device specifications

• accuracy considerations

• visual inspection

• mechanical inspection

• connecting devices

Understanding the information in this chapter will help you successfully operate the instrument.

CAUTION

The input circuits can be damaged by electrostatic discharge (ESD). Therefore, avoid applying static discharges to the front-panel input connectors. Before connecting any coaxial cable to the connectors, momentarily short the center and outer conductors of the cable together. Avoid touching the front-panel input connectors without first touching the frame of the instrument. Be sure the instrument is properly earth-grounded to prevent buildup of static charge.

2-2

Care and Handling of Precision Connectors

3.5 mm Connector Care

This chapter shows you how to take care of 3.5 mm connectors so that you can maintain high levels of accuracy, repeatability, and system performance. Taking appropriate care of your connectors will also extend their service life. Most of the information can also be applied to 2.4 mm connectors. For additional information on 2.4 mm connectors, refer to operating note "2.4 mm Adapters and Calibration Accessories" Agilent part number 11900-90903.

Connector Wear

Connector wear will eventually degrade performance. The calibration devices, which are typically used only a few times each day, should have a very long life. However, because the connectors often undergo many connections a day, they wear rapidly. Therefore, it is essential that all connectors on the Agilent 54753A or 54754A TDR plug-in modules be inspected regularly, both visually (with a magnifying glass) and mechanically (with a connector gage), and replaced as necessary. Procedures for visual and mechanical inspection are given in the next section of this manual. It is easier and cheaper to replace a worn adapter than a worn channel connector.

Operator Skill

Operator skill in making good connections is essential. The mechanical tolerances of the precision 3.5 mm connectors used in the Agilent 54007A kit are two or three times better than the tolerances in regular 3.5 mm connectors. Slight errors in operator technique that would go unnoticed with regular connectors often appear with precision connectors in the calibration kit. Incorrect operator technique can often result in lack of repeatability. Carefully study and practice the connection procedures that are explained later in this manual until your calibration measurements are consistently repeatable.

Device Specifications

Electrical specifications depend upon several mechanical conditions. A 3.5 mm connector is a precision connector dedicated to very specific tolerances. SMA connectors are not precision mechanical devices. They are not designed for repeated connections and disconnections and are very susceptible to

2-3

Care and Handling of Precision Connectors

Device Specifications

mechanical wear. They are often found, upon assembly, to be out of specification. This makes them potentially destructive to any precision 3.5 mm connectors to which they might be mated.

Use extreme caution when mating SMA connectors with 3.5 mm precision connectors. Prevent accidental damage due to worn or out-of-specification SMA connectors. Such connectors can destroy a precision 3.5 mm connector, even on the first connection.

Agilent Technologies recommends that you keep three points clearly in mind when you mate SMA and precision 3.5 mm connectors: SMA inspection, alignment, and mechanical mismatch.

SMA Inspection

Before mating an SMA connector (even a new one) with a precision 3.5 mm connector, carefully inspect the SMA connector, both visually and mechanically with a precision connector gauge designed to measure SMA connectors. A male SMA connector pin that is too long can smash or break the delicate fingers on the precision 3.5 mm female connector. Gauging SMA connectors is the most important step you can take to prevent damaging your equipment.

Alignment

Be careful when aligning the connectors. Push the two connectors together with the male contact pin precisely concentric with the female. Do not overtighten or rotate either center conductor. Turn only the outer nut of the male connector and use a torque wrench (5 lb.in., 60 N-cm) for the final connection. Note that this torque is less than that when mating precision 3.5 mm connectors with each other. A torque wrench suitable for SMA connectors preset to 5 lb.in. is available (Agilent part number 8710-1582, CD 0).

The TDR plug-in modules come with adaptors already installed to prevent damage to the channel connectors. Then, if accidental damage does occur, the adapter is all that needs to be replaced. It is easier and cheaper to replace a damaged adapter than a channel connector. SMA connectors can then be mated with precision 3.5 mm connectors without difficulty or fear of expensive and time-consuming repairs.

Mechanical Mismatch

Significant structural and dimensional differences exist between these two types of connectors. Precision 3.5 mm connectors, also known as APC-3.5 connectors, are air-dielectric devices. Only air exists between the center and outer conductors. The male or female center conductor is supported by a plastic "bead" within the connector. In SMA connectors, a plastic dielectric supports

2-4

Figure 2-1

Care and Handling of Precision Connectors

Device Specifications

the entire length of the center conductor. In addition, the diameter of both the center and outer conductors of an SMA connectors differ from that of a precision

3.5 mm connector.

If these precautions and recommendations are followed, SMA connectors can be mated with 3.5 mm precision connectors without fear of expensive and time consuming repairs.

SMA and a Precision 3.5 mm Connectors

When an SMA connector is mated with a precision 3.5 mm connector, the connection exhibits a continuity mismatch (SWR), typically about 1.10 at 20 GHz. This mismatch is less than when precision 3.5 mm connectors are mated. Keep this fact in mind when making measurements on SMA and precision 3.5 mm coupled junctions.

2-5

Figure 2-2

Care and Handling of Precision Connectors

Accuracy Considerations

Typical SWR of SMA and Precision 3.5 mm Connectors

Accuracy Considerations

Accuracy requires that 3.5 mm precision connectors be used. However, SMA connectors can be used if special care is taken when mating the two, and all connectors are undamaged and clean. Before each use, the mechanical dimensions of all connectors must be checked with a connector gauge to make sure that the center conductors are positioned correctly. All connections must be made for consistent and repeatable mechanical (and therefore electrical) contact between the connector mating surfaces.

Carefully study and practice all procedures in this chapter until you can successfully perform them repeatedly. Accuracy and repeatability are critical for good high frequency measurements. Note that the device connection procedures differ in several important ways from traditional procedures used in the industry. Agilent Technologies procedures have been developed through careful experimentation.

2-6

Care and Handling of Precision Connectors

Accuracy Considerations

Handling Precision 3.5 mm Connectors

• Precision 3.5 mm connectors must be handled carefully if accurate calibrations and measurements are to be obtained.

• Store the devices in the foam-lined storage case when not in use.

• Avoid bumping or scratching any part of the mating surfaces.

• Be careful to align the center connectors.

• Check the alignment carefully before tightening the connector nuts.

• Use a torque wrench for all final connections in order to avoid

overtightening.

• Support the devices being used in order to avoid vertical or lateral force on any connectors. This precaution is critical when using the airline, 6 cm "L", or cables.

When Disconnecting Devices:

• Do not rock or bend any connections.

• Pull the connector straight out without unscrewing or twisting.

• Before storage, screw the connector nut all the way out to help protect the

surfaces, and use the plastic caps provided. These plastic caps can be taken off easily by unscrewing, rather than pulling.

CAUTION Do not use a damaged or defective connector. It will damage any good

connector to which it is attached. Throw the connector away or have it repaired.

A connector is bad if it fails either the visual or mechanical examinations or when an experienced operator cannot make repeatable connections. The time and expense involved in replacing channel connectors warrants considerable caution when any connector might be less than perfect.

If any doubts exist about a connector, call your Agilent Technologies representative. Agilent Technologies field offices offer limited professional advice and have access to the factory for information.

2-7

Care and Handling of Precision Connectors

Visual Inspection

Always begin a calibration with a careful visual inspection of the connectors, including the test set connectors to make sure they are and undamaged.

CAUTION

Make sure that you and your equipment are grounded before touching any center conductor so you won't cause static electricity and create a potential for electrostatic discharge. When using or cleaning connectors, be aware that you are touching exposed center connectors that are connected directly to the internal circuits of the oscilloscope. Touching the center conductor, especially with a wiping or brushing motion, can cause an electrostatic discharge (ESD) and severely damage these sensitive circuits.

Use an illuminated, 4-power magnifying glass for visual inspection.

1

Before you begin, make sure you and any equipment you are using are grounded to prevent electrostatic discharge.

2

Examine the connectors first for obvious problems, such as deformed threads, contamination, or corrosion.

3

Next concentrate on the mating surfaces of each connector. Look for scratches, rounded shoulders, misalignment, or any other signs of wear or damage.

4

Make sure that the surfaces are clean, free of dust and solvent residues. Dirt or damage visible with a 4-power magnifying glass can cause degraded electrical performance and possible connector damage. All connectors should be repaired or discarded immediately.

Mechanical Inspection

Mechanical inspection of the connectors is the next step. This inspection consists of using the appropriate male or female precision 3.5 mm connector gauge to check the mechanical dimensions of all connectors, including those on the test set. The purpose of doing this is to make sure that perfect mating will occur between the connector surfaces. Perfect mating assures a good electrical match and is very important mechanically to avoid damaging the connectors themselves, especially on the oscilloscope.

2-8

Care and Handling of Precision Connectors

Mechanical Inspection

Center Conductor

The critical dimension to be measured is the recession of the center conductor. This dimension is shown as MP and FP in Figure 2-3 and Figure 2-4. No protrusion of the center conductor's shoulder is allowable on any connector. The maximum allowable recession of the center conductor shoulder is 0.003 in. (0.08 mm) on all connectors, except those on the channel connectors.

On the channel connectors, not only is no protrusion allowable, the shoulder of the center conductor must be recessed at least 0.0002 in. (0.005 mm). The maximum allowable recession of the center conductor shoulder on the channel connectors is 0.0021 in. (0.056 mm).

2-9

Figure 2-3

Care and Handling of Precision Connectors

Mechanical Inspection

D = inside diameter of the outer conductor

d = diameter of male/female center connector

A = outside diameter of outer conductor at the mating plane

r = corner relief for male connector

B = protrusion of the male contact pin tip beyond the outer conductor mating plane

C = recession of the outer conductor mating plane behind outer face of connector

MP = recession of male contact pin shoulder behind outer conductor mating plane

Male Connectors Female Connectors

inches millimeters inches millimeters

D = 0.1378 ± 0.0005 3.500 ± 0.013 D = 0.1378 ± 0.0005 3.500 ± 0.013 d = 0.0598 ± 0.0003 1.519 ± 0.008 d = 0.0598 ± 0.0003 1.519 ± 0.008 A = 0.1803 + 0.000

- 0.002 r = 0.003 0.08 r = 0.003 0.08 B = 0.085 +0.005

- 0.015 C = 0.120 ± 0.015 3.05 ± 0.38 C = 0.176 ± 0.002 1.93 ± 0.05 Mp = 0.00 + 0.003

- 0.000 dm = 0.037 + 0.000

- 0.001

Mechanical Dimensions of Connector Faces

4.580 + 0.00

- 0.05

2.16 + 0.13

- 0.38

0.000 + 0.08

- 0.00

0.94 + 0.00

- 0.03

A = 0.1807 + 0.002

- 0.000

N/A

Fp = 0.000 + 0.003

- 0.00

N/A

4.590 + 0.05

- 0.00

0.000 + 0.08

- 0.00

2-10

Figure 2-4

Care and Handling of Precision Connectors

Mechanical Inspection

Mechanical Dimensions of the Short Circuit

Outer Conductor

If any contact protrudes beyond the outer conductor mating plane, the contact is out of tolerance and must be replaced. If the center conductor is not recessed at least 0.0002 in. (0.005 mm), it is out of tolerance and must be replaced. In both cases the out-of-tolerance connector will permanently damage any connector attached to it. Destructive electrical interference will also result due to buckling of the female contact fingers. This is often noticeable as a power hole several dB deep occurring at about 22 GHz.

If any contact is recessed too far behind the outer conductor mating plane (0.0021 in. 0.056 mm, except in test sets), poor electrical contact will result, causing high electrical reflections. Careful gauging of all connectors will help prevent this condition.

Before using the connector gauge to measure the connectors, visually inspect the end of the gauge and the calibration block in the same way that you inspected the connectors. Dirty or damaged gauge facings can cause dirty or damaged connectors. Two connector gauges are available from Agilent Technologies, one for each connector type, male and female. Refer to

Figure 2-5. A single gauge calibration block is used to zero both gauges; one end

protrudes for zeroing the male connector gauge. The part number for both gauges, as well as the calibration block is 85052-80010.

Figure 2-5 to Figure 2-8 show how to use the connector gauges. Zero the gauge

with the calibration block. Refer to Figure 2-5. It is recommended that you zero both gauges first, then measure each of the terminations and/or adapters that will be used. Then, as the last step, measure the channel connectors.

Figure 2-7 and Figure 2-8 show how to measure precision 3.5 mm connectors.

Note that a plus (+) reading on the gauge indicates recession of the center conductor and a minus (-) reading indicates protrusion. Since no protrusion of either connector is allowable, readings for connectors within the allowable

2-11

Figure 2-5

Care and Handling of Precision Connectors

Mechanical Inspection

range will be on the plus (+) scale of the gauge. Also note that the allowable tolerance range for the test set connectors is different from the range for other connectors. Both ranges are shown in Figure 2-7 and Figure 2-8. Before measuring test set connectors, be sure that the power to the test set is off and that you and your equipment are grounded to prevent electrostatic discharge.

Precision 3.5 mm Connector Gauges

2-12

Figure 2-6

Care and Handling of Precision Connectors

Mechanical Inspection

Zeroing Precision 3.5 mm Connector Gauge

2-13

Figure 2-7

Care and Handling of Precision Connectors

Mechanical Inspection

Measuring Precision 3.5 mm Male Connectors

2-14

Figure 2-8

Care and Handling of Precision Connectors

Mechanical Inspection

Measuring Precision 3.5 mm Female Connectors

2-15

Care and Handling of Precision Connectors

Connecting the Devices

Figure 2-9 and Figure 2-10 illustrate Agilent Technologies’ recommended

procedures for making connections with the calibration devices. Notice that these recommended procedures differ from traditional procedures used in the microwave industry, especially the counter-rotation technique and procedure for connecting the airline.

The counter-rotation technique, recommended here, involves a slight rotation of the termination or adapter just before the final tightening of the connector nut. This eliminates the very small air wedge between the outer conductors that frequently occurs when the body is held stationary during tightening, as it is in the traditional procedure. The Agilent 54753A or Agilent 54754A plug-in modules will detect the reflections caused by such small wedges.

The counter-rotation technique does not harm the connectors. The gold plating on the outer conductor surface will become burnished in time. This is normal, and as long as the surface remains smooth, the connector is still good. After much use the gold plating may eventually wear through and expose the beryllium-copper substratum. This too is normal, and if it is smooth the connector is still good, although the beryllium-copper surface may oxidize if the connector is used infrequently.

If the burnished surface is rough, scratched, rippled, or has other irregularities, too much tightening force is being used. If the roughness is severe, the connector is ruined and should not be used.

CAUTION

Damage can result if SMA connectors are overtightened to precision 3.5 mm connectors. Use a torque wrench designed for SMA connectors, set to a 5 in lb (60 N/cm). A torque wrench suitable for SMA connectors is available, Agilent part number 8710-1582.

2-16

Care and Handling of Precision Connectors

Connecting the Devices

Counter-Rotation Technique

The recommended Agilent Technologies counter-rotation technique is for precision 3.5 mm connectors. Before making any connections to the channel connectors, ground yourself with a grounded wrist strap. Also, it is good practice to grasp the outer shell of the test port before you make any connections to the channel connectors in order to discharge any static electricity on your body. This is the most effective single safeguard to prevent ESD damage to your instruments.

If the device has a retractable connector nut, fully retract the nut before

1

mating the connectors. Carefully align the male and female contact pins and slide the connectors straight together until the center and the two outer conductors meet. Be careful not to twist or bend the contact pins. You should feel a slight resistance as the connectors mate.

Make the preliminary connection by attaching the connector nut of the

2

male connector to the female. The male connector is held stationary as the female connector is tightened and draws the male pin into the female connector. Refer to

Figure 2-9

. Any other method used may cause the male pin to damage the female connector. Support the body of the device and turn the connector nut until the mating surfaces make light contact. Do not overtighten. All you want is a connection of the outer conductors with gentle contact at all points of both mating surfaces.

Figure 2-9

Connecting 3.5 mm Devices

2-17

Figure 2-10

Care and Handling of Precision Connectors

Connecting the Devices

3 When you are satisfied with this preliminary connection, use the

following counter-rotation technique to eliminate air wedges between the mating planes. Refer to

Figure 2-10

. If the calibration device is male, hold the connector nut firmly. Very slowly rotate the body of the device about 10-20 ° counterclockwise. Note that this slight rotation or backwiping is sufficient. Greater rotation does not improve electrical performance and increases wear on the connector surfaces.

Counter-rotation Technique

If the calibration device is female (the connector nut is on the TDR plug-in module), very slowly rotate both the connector nut and the body of the device clockwise 10-20 ° (counterclockwise rotation will loosen the connection).

Light, smooth frictional resistance felt during the counter-rotation indicates you have made the preliminary connection correctly and that the counter-rotation technique has been successful. Roughness felt during counter-rotation indicates either that the connectors are damaged or that there is roughness in the connector nut/thread contact. Inspect both connectors again before proceeding, to make sure that the roughness is due to roughness in the connector nut interface rather than on the connector mating planes.

4 Tighten the connector nut finger tight, allowing the device to turn with

the nut if it tends to do so. A small rotation of the body of the device at this point is acceptable and tends to occur naturally.

5 Use a torque wrench to make the final connection. Use of the torque

wrench assures the final connection will be tight enough for optimum electrical performance, but not so tight as to distort or damage the connectors.

2-18

Care and Handling of Precision Connectors

Connecting the Devices

To disconnect, follow this procedure:

1 Loosen the connector nut on the male connector with the torque

wrench. Leave the connection finger tight.

2 While supporting the calibration device, gently unfasten the connectors

and pull the calibration device straight out of the channel connector. Do not twist either the center conductor or the outer conductor housing or exert lateral or vertical (bending) force on the connection.

Some precision 3.5 mm female connector fingers are very tight and can pull the center pin of their mates out past specifications as they are disconnected. If such a male pin is inserted into a female connector, it can cause considerable damage by pushing the female center conductor back too far. Be aware of this possibility and check all connectors before mating them again.

2-19

2-20

3

Setup Channel Menu

What you’ll find in this chapter

This chapter describes the Setup Channel menu. A key tree and description of the available functions are included.

CAUTION

The input circuits can be damaged by electrostatic discharge (ESD). Therefore, avoid applying static discharges to the front-panel input connectors. Before connecting any coaxial cable to the connectors, momentarily short the center and outer conductors of the cable together. Avoid touching the front-panel input connectors without first touching the frame of the instrument. Be sure the instrument is properly earth-grounded to prevent buildup of static charge.

The top left keys of the plug-in module are the Channel keys. These keys give you access to the Setup Channel menu for each input. The Setup Channel menu is displayed on the right side of the screen when the Channel key is pressed. There are several types of softkeys available. A description of the different softkeys and their functions is provided in the Agilent 83480A, 54750A User’s Quick Start Guide supplied with the mainframe.

3-2

Figure 3-1

Setup Channel Menu

Electrical Setup Channel menu.

3-3

Setup Channel Menu

Displaying the Setup Channel menu

To display the Setup Channel menu, press the Channel key.

Display

The Display softkey turns the channel display off and on. When the channel display is on, a waveform is displayed for that channel, unless the offset is adjusted so the waveform is clipped off of the display or the instrument is not triggering.

The channel number, vertical scaling, and offset are displayed at the bottom left of the waveform area. They remain on the display until the channel is turned off, or an automatic measurement is performed. The automatic measurement results share the same area of the display as the channel setups.

When the channel display is off, the waveform display for that channel is turned off, pulse parameter measurements are stopped and acquisition on that channel is stopped, unless it is needed as an operand for waveform math functions or TDR/TDT responses.

Even though the channel display is off, you can still use the plug-in as a function source in the Math menu or as a source for four normalize, differential, or common mode responses. However, the instrument will not trigger unless one or more of the other channel displays are turned on, or unless a math function or TDR/TDT response is using one of the channels.

Key Path Channel Display

Scale

The Scale softkey controls the vertical scaling of the waveform. If the fine mode is off, then the knob and arrow keys change the vertical scaling in a 1-2-5 sequence. When fine mode is on, the knob and arrow keys change the vertical scaling in 1 mV increments. You can also use the keypad to enter values in 1 mV increments, independent of the fine mode selection.

The units the scale is displayed in depend on the unit of measure selected with the Units softkey. The choices for units are volts, watts, amperes, ohms, % reflect, gain, or unknown.

3-4

When the ohm, % reflect, or gain units are selected, the control changes to Magnify scale. In this mode of operation, the TDR plug-in’s hardware scale behaves as it would when the units mode is selected for all stimulus except for differential or common mode.

If the TDR/TDT stimulus is set to differential or common mode, the control also changes to Magnify scale. However, the hardware scale is set so that the displayed waveform is never clipped. The Magnify scale control is a software scaling control.

Key Path Channel Scale

Offset

The Offset softkey moves the waveform vertically. It is similar to the position control on analog oscilloscopes. The advantage of digital offset is that it is calibrated. The offset voltage is the voltage at the center of the graticule area, and the range of offset is 500 mV. You can use the knob, arrow keys, or keypad to change the offset setting. The fine mode also works with offset.

When an Agilent 54700-series active probe is used with the plug-in module and is connected to the probe power connector adjacent to the channel input, the offset control adjusts the external scale factor and offset of the hybrid inside the active probe. A probe connected to the auxiliary power connector adjacent to the trigger input will function, but the channel scale factor will not be adjusted automatically.

The units the offset is displayed in depend on the unit of measure selected with the Units softkey. The choices for units are volts, watts, amperes, ohms, % reflect, gain, or unknown.

When the ohm, % reflect or gain units are selected, the control changes to Magnify offset. In this mode of operation, the TDR plug-in’s hardware offset behaves as it would when the units mode is selected for all stimulus except for differential or common mode.

If the TDR/TDT stimulus is set to differential or common mode, the control also changes to Magnify offset, however, the harrower scale is set so that the displayed waveform is never clipped. The Magnify offset control is a software offset control.

Setup Channel Menu

Offset

Key Path Channel Offset

3-5

Setup Channel Menu

Bandwidth. . .

You can use the Bandwidth function to select either 12.4 GHz or 18 GHz bandwidth. For the Agilent 54753A TDR plug-in module, channel 2 can be either

12.4 GHz or 20 GHz bandwidth.

Key Path Channel Bandwidth. . .

Alternate scale. . .

The Alternate Scale function allows you to change the units used to label the vertical scale of the display. It also allows you to select the attenuation units and the attenuation factor.

Key Path Channel Alternate scale . . .

Atten units

The Atten Units function lets you select how you want the probe attenuation factor represented. The choices are either decibel or ratio. The formula for calculating decibels is:

20

V

out

----------

V

or 10

in

P

out

----------loglog

P

in

The Atten Units function is not available when the units are set to ohm, % reflect, or gain.

Attenuation

The Attenuation function lets you select an attenuation that matches the device connected to the instrument. When the attenuation is set correctly, the instrument maintains the current scale factors, if possible. All marker values and voltage or wattage measurements will reflect the actual signal at the input to the external device.

3-6

The attenuation range is from 0.0001:1 to 1,000,000:1. When you connect a compatible active probe to the probe power connector, adjacent to the corresponding channel input, the instrument automatically sets the attenuation. For all other devices, set the probe attenuation with the knob, arrow keys, or keypad.

Refer to “Calibrating Voltage Probes” on page 3-12 for information on calibrating to the tip of the probe.

The Attenuation function is not available when ohm, % reflect, or gain units are selected.

Key Path Channel Alternate scale . . . Attenuation

Units

The Units function lets you select the unit of measure appended to the channel scale, offset, trigger level, and vertical measurement values. For the plug-in module, the units are volts, watts, amperes, ohms, % reflect, gain, or unknown. Use volt for voltage probes, ampere for current probes, watt for optical-toelectrical (O/E) converters, and unknown when there is no unit of measure or when the unit of measure is not one of the available choices. The gain selection is only available when the channel has been chosen as a TDT destination.

The two additional choices, ohms and % reflect are selectable once a TDR/TDT normalization and reference plane have been established (see the 54753A Setup Menu or 54754A Setup Menu chapter under Establish normalization & ref plane for more information). Use Ohms when TDR/TDT vertical scale units of ohms/ div are required for making measurements. Use % reflect when TDR/TDT percentage of reflection units are required.

Setup Channel Menu

Alternate scale. . .

Key Path Channel Alternate scale . . . Units

Ext gain and Ext offset

When you select ampere, watt, or unknown, two additional functions become available: External Gain and External Offset. These two additional functions allow you to compensate for the actual characteristics of the probe rather than its ideal characteristics. For example, you might have an amplified lightwave converter with ideal characteristics of 300 V/W with 0 V offset. But, its actual characteristics are 324 V/W with 1 mV of output offset. Therefore, set the External Gain to 324 V/W and the External Offset to 1 mV.

3-7

Setup Channel Menu

Calibrate . . .

Key Path Channel External scale . . . Units Volt Ext gain or Ext Offset

Channel External scale . . . Units Watt Ext gain or Ext Offset Channel External scale . . . Units Unknown Ext gain or Ext Offset

Calibrate . . .

The calibrate menu allows you to null out any skew between probes or cables and to check the present calibration status of the instrument.

Key Path Channel Calibrate . . .

Skew

The Skew function changes the horizontal position of a waveform on the display. The Skew function has a range of approximately 100 µs. You can use skew to compensate for differences in cable or probe lengths. It also allows you to place the triggered edge at the center of the display when you are using a power splitter connected between the channel and trigger inputs. Another use for skew is when you are comparing two waveforms that have a timing difference between them. If you are more interested in comparing the shapes of two waveforms rather than the actual timing difference between them, you can use Skew to overlay one waveform on top of the other waveform.

To adjust the skew on two channels

1. Turn both channels on and overlay the signals vertically.

2. Expand the time base, so the rising edges are about a 45 degree angle.

3. Adjust the skew on one of channels, so that the rising edges overlap at the 50 percent points.

Key Path Channel Calibrate . . . Skew

3-8

Setup Channel Menu

Calibrate . . .

TDR Skew

The TDR Skew function changes the position of the TDR step. The TDR Skew function has a range of ≅ ±400 pS. The units of the function are shown in % of the maximum range, or ±100%. The Skew function and the TDR Skew function differ in that Skew moves the acquired waveform with respect to the trigger, while the TDR Skew function moves the TDR step with respect to the trigger. TDR Skew can be used to align the TDR steps of the two TDR channels for more accurate differential TDR measurements when cable or probe lengths are different.

To deskew the two TDR channels

1. Turn on both channels and overlay the signals vertically with no cables attached.

2. Expand the time base so the rising edges are about a 45 degree angle.

3. Adjust the TDR skew on one of the channels, so that the rising edges overlap at the 50 percent points.

4. Attach the cables. If the cables differ in length, then the waveforms will not overlay each other.

5. Using the ∆Time auto measurement or manual markers, measure the ∆time (the skew) between the TDR channels.

6. Adjust the channel Skew for the channel whose waveform is to the right of the other channels waveform until the skew is ½ of the measured ∆time.

7. Adjust the TDR Skew for the right most waveform until the remaining skew is ≅ 0.

Key Path Channel Calibrate . . . TDR Skew

3-9

Setup Channel Menu

Calibrate . . .

Cal status

The Cal Status function displays a screen similar to Figure 3-8.

Key Path Channel Calibrate Cal Status

Figure 3-8

A typical Cal Status display.

Current Date This is the current date and time. You can compare this to the last plug-in module calibration time. That way you will know how long it has been since the last plug-in module calibration was performed.

Current Frame ∆Temp This is the temperature change on the inside of the instrument since the last mainframe calibration was performed. A positive number indicates how many degrees warmer the mainframe is currently as compared to the temperature of the mainframe at the last mainframe calibration.

3-10

Channel 1 Calibration Status The instrument displays Calibrated when the plug-in module has been calibrated in the current mainframe slot otherwise the instrument displays Uncalibrated. Once a plug-in is calibrated, the temperature difference (∆Temp) between when the plug-in was calibrate and the current temperature is displayed. The plug-in module will met dc accuracy specifications as long as the ∆Temp is within the range of -5 °C to +5 °C. Also displayed, is a list of the plug-in module’s model number, serial number, date of last calibration, and time of last calibration.

Calibrate probe

Connect a voltage probe to the plug-in and then press:

Calibrate probe Continue

The instrument calibrates to the tip of the probe by setting the probe attenuation to the actual attenuation ratio of the probe. The instrument also automatically compensates for any offset that the probe may introduce.

Key Path Channel Calibrate Calibrate probe Continue

Setup Channel Menu

Calibration Procedures

What you’ll find in this section

This sections contains procedures for performing:

• a plug-in module vertical calibration

• calibration of voltage probes

• calibration of other devices

3-11

Setup Channel Menu

Performing a Plug-in Module Vertical Calibration

1

To perform a plug-in module vertical calibration, press:

Utility

Calibrate . . . Calibrate plug-in. . .

2

Select the plug-in module to be calibrated by pressing:

1 and 2 or 3 and 4

3

Start the calibration procedure by pressing:

Start cal

4

Follow the on screen instructions.

Calibrating Voltage Probes

Because the mainframe’s CAL signal is a voltage source, you can let the instrument compensate for the actual characteristics of your probe by letting the instrument calibrate to the tip of the probe.

Performing the Calibration

To calibrate a voltage probe to the probe tip, set the instrument as follows:

Atten units ratio Units Voltage Calibrate Probe

The instrument automatically calibrates to the tip of the probe, sets the probe attenuation and compensates for any probe offset.

Calibrating Other Devices

Because the mainframe’s CAL signal is a voltage source, it cannot be used to calibrate to the probe tip when the units are set to ampere, watt, or unknown. Instead, set the external gain and external offset to compensate for the actual characteristics of the probe or device. If you do not know the actual characteristics, you can refer to the typical specifications that came with the probe or device.

3-12

Setup Channel Menu

Calibrating Voltage Probes

Performing the Calibration

To compensate for the actual characteristics of the probe or device, set the instrument as follows:

Atten units ratio Attenuation 1:1 Units Ampere Ext gain actual gain characteristics of the probe or device. Ext offset offset introduced by the probe or device.

(Watt or unknown)

3-13

3-14

4

Agilent 54753A TDR/TDT Setup Menu

What you’ll find in this chapter

This chapter describes the TDR/TDT Setup menu. A key tree and description of the available functions is included.

CAUTION

The input circuits can be damaged by electrostatic discharge (ESD). Therefore, avoid applying static discharges to the front-panel input connectors. Before connecting any coaxial cable to the connectors, momentarily short the center and outer conductors of the cable together. Avoid touching the frontpanel input connectors without first touching the frame of the instrument. Be sure the instrument is properly earth-grounded to prevent buildup of static charge.

The top right key of the plug-in module is the TDR/TDT Setup key. This key gives you access to the TDR/TDT Setup menu. The TDR/TDT Setup menu is displayed on the right side of the screen when the TDR/TDT Setup key is pressed. There are several types of softkeys available.

4-2

Figure 4-1

Agilent 54753A TDR/TDT Setup Menu

TDR/TDT Setup Stimulus

TDR/TDT help . . .

TDT 1 dest

Normalize response . . .

Off

On

External

Cancel

Enter

Single ended TDR/TDT

Differential common mode TDR/TDT

Done

channel 2

none

Cancel

Enter

Risetime

TDR/TDT

TDR normalize

TDR

TDT

off

on

TDR/TDT Setup Menus

TDR rate automatic . . . (250 kHz)

Preset TDR/TDT

Establish normalization & ref plane

Done

automatic

manual TDR rate

Done

4-3

Table 4-1

Agilent 54753A TDR/TDT Setup Menu

Displaying the TDR/TDT Setup Menu

To display the TDR/TDT Setup menu, press the TDR/TDT Setup key on the TDR plug-in module.

Stimulus

Pressing the Stimulus softkey produces a pull-down menu used to turn on or turn off the TDR step. The Agilent 54753A is a single-ended TDR plug-in and has one TDR stimulus channel. The following table contains a list of the available stimulus menu choices and their descriptions.

Stimulus Menu Choices

Stimulus Description

off Turns the TDR step off and disables the TDR measurement system.

on Turns the TDR step on and enables the TDR measurement system.

external This setup provides control for and requires an external step

Key Path TDR/TDT Setup Stimulus

generator before measurements can be made.

TDT 1 dest

The TDT 1 dest softkey only appears when the Stimulus is set to on or external. Pressing the TDT 1 dest softkey produces a pull-down menu used to select the channel used as the destination channel for TDT measurements. The choices available for this pull-down menu depend on the other TDR or electrical plugin, if any, in the mainframe.

Any electrical channel is a valid TDT destination channel. If external stimulus is selected, the TDT destination may not be set to the currently defined TDR destination channel.

4-4

If no other valid TDT destination channels are available, then "none" is the only choice. If a TDT destination other than none is selected, then the Preset TDR/TDT control will turn on and preset the TDT destination channel.

Key Path TDR/TDT Setup TDT 1 dest

TDR 1 dest

The TDR 1 dest softkey only appears when the stimulus is set to external. Pressing the TDR 1 dest softkey produces a pull-down menu used to select the channel used as the destination channel for TDR measurements. Any electrical channel is a valid TDR destination channel. The TDR destination may not be set to the currently defined TDT destination.

Key Path TDR/TDT Setup TDR 1 dest

Normalize response . . .

Agilent 54753A TDR/TDT Setup Menu

TDR 1 dest

The Normalize response function allows you to change the risetime of the normalized step, to select TDR and TDT normalization, to turn on or off the display of the normalized TDR or TDT trace, to change the scaling of the normalized trace, and to establish the normalization filter values and reference plane.

Risetime

The Risetime function allows you to change the normalized step’s risetime from a minimum of

10 ps

or

time per division (s/div) 10 divisions×

min 8 points

whichever is greater, to a maximum of

max 5 time per division (s/div)×=

------------ ------------- ------------- ---------- ------------- ------------- ------------- ------

×=

record length

4-5

Agilent 54753A TDR/TDT Setup Menu

Normalize response . . .

While the TDR step’s risetime applied to the system under test is fixed, the measured response has a set of mathematical operations applied to it. These mathematical operations effectively change the displayed response to the system just as if a different TDR step risetime had actually been applied. This allows you to select a risetime for TDR/TDT measurements that is close to the actual risetime used in your system. This risetime value applies to both TDR and TDT normalized channels. For more information on normalization, see the chapter titled Improving Time Domain Network Measurements.

Key Path TDR/TDT Setup Normalize response . . . Risetime

TDR/TDT

The TDR/TDT function is used to select between TDR and TDT for normalization. Both TDR and TDT channels can be normalized. This control selects which normalized trace is referred to for the following controls. Before TDT normalization can be done, you must select a TDT destination (TDT 1 dest).

Key Path TDR/TDT Setup Normalize response . . . TDR/TDT

TDR or TDT normalize

The TDR normalize function is available if the TDR mode is selected by using the previous control; otherwise, the TDT normalize function is available. In either case, this function turns on or off the display of the normalized trace. The TDR and TDT normalization functions can be on at the same time.

Key Path TDR/TDT Setup Normalize response . . . TDR normalize

Normalize scaling . . .

The Normalize scaling function is used when vertical and horizontal scaling of the normalized response is required that is independent from that of the source channel. This function only appears when TDR or TDT normalize is set to on.

Key Path TDR/TDT Setup Normalize response . . . Normalize scaling . . .

Vertical There are two choices for vertical mode: track source and manual. The track source mode sets the control of the vertical scaling for the normalized trace to that of the source channel. When manual mode is selected, the Y Scale and Y Offset menus appear allowing you to independently change the vertical scale and offset of the normalized trace.

Key Path TDR/TDT Setup Normalize response . . .Normalize scaling . . . Vertical

4-6

Agilent 54753A TDR/TDT Setup Menu

Normalize response . . .

Horizontal There are two choices for horizontal mode: track source and manual. The track source mode sets the control of the horizontal scaling

for the normalized trace to that of the source channel. When manual mode is selected, the Y Scale and Y Position menus appear allowing you to independently change the horizontal scale and position for the normalized trace.

Key Path TDR/TDT Setup Normalize response . . .Normalize scaling . . . Horizontal

Establish normalization & ref plane

The Establish normalization & ref plane function establishes the filter values used to normalize a channel and to set the reference plane for TDR and TDT measurements. This function must be performed separately for TDR and TDT modes. The normalization and reference plane must be re-established when power is lost or when the instrument is turned off. However, the values used for normalization and reference plane calculations can be stored to and re-loaded from disk. (See the Disk Menu chapter in the Agilent 83480A, Agilent 54750 User’s Guide for more information.)

The normalization filter values and reference plane become invalidated when the timebase scale, record length or channel bandwidth is changed. Also, the normalization process will not be able to remove small synchronous noise in the channels baseline if the timebase position is changed. For most measurements this error is very small.

The reference plane must be established before ohm, % reflect or gain units are selectable for the channel. Also, the Reference ref plane available in the Marker menu.

The function steps you through the normalization and reference plane procedure for the selected measurement type. The procedure steps are displayed at the top of the screen. The items required for calibration are shown in Tabl e 4-2 .

function is not

4-7

Agilent 54753A TDR/TDT Setup Menu

TDR rate automatic . . . (250 kHz)

Table 4-2

Establish normalization & ref plane Hardware Requirements

Measurement Requirements

TDR 50 ohm 3.5 mm SMA terminator

3.5 mm SMA short

TDT 1 or 2 each 3.5 mm SMA cables

3.5 mm barrel connector

Key Path TDR/TDT Setup Normalize response . . . Establish normalization & ref plane . . .

TDR rate automatic . . . (250 kHz)

The TDR rate automatic . . . (250 kHz) function allows you to manually or automatically select the repetition rate of the TDR step. The range of values for manual mode selection are from 50 Hz to 250 kHz repetition rate using a 1-2-5 sequence. When this function is set to automatic, the TDR step repetition rate varies automatically as the Time base Scale is changed to keep multiple steps off screen. As the TDR rate decreases, TDR measurements can be made on longer transmission lines.

Key Path TDR/TDT Setup TDR rate automatic

Key Path TDR/TDT Setup TDR rate manual

Preset TDR/TDT

The Preset TDR/TDT function prepares the oscilloscope for making TDR/TDT measurements by automatically setting several menu fields. The TDR preset feature appears in the TDR/TDT Setup menu once a stimulus has been selected. The menus that are affect by this feature are shown in Table 4-3.

4-8

Table 4-3

Agilent 54753A TDR/TDT Setup Menu

Preset TDR/TDT

Preset TDR/TDT Configuration

Menu Menu Item Set To

Acquisition Averaging on

Best Flatness

Time Base Scale 500.0 ps/div

Position Set to a value which places the

incident edge on screen.

Channel 1 Setup Display on

Scale 100 mV/div

Offset 200.0 mV (for Stimulus on)

0.0 mV (form Stimulus external)

Bandwidth 12.4 GHz (for Stimulus on)

18.0 GHz (for Stimulus external)

Attenuation units ratio

Attenuation 1.000 : 1

Key Path TDR/TDT Setup Preset TDR/TDT

4-9

4-10

5

Agilent 54754A TDR/TDT Setup Menu

What you’ll find in this chapter

This chapter describes the Agilent 54754A TDR/TDT Setup menu. A key tree and description of the available functions is included.

CAUTION

The input circuits can be damaged by electrostatic discharge (ESD). Therefore, avoid applying static discharges to the front-panel input connectors. Before connecting any coaxial cable to the connectors, momentarily short the center and outer conductors of the cable together. Avoid touching the frontpanel input connectors without first touching the frame of the instrument. Be sure the instrument is properly earth-grounded to prevent buildup of static charge.

The top right key of the plug-in module is the TDR/TDT Setup key. This key gives you access to the TDR/TDT Setup menu. The TDR/TDT Setup menu is displayed on the right side of the screen when the TDR/TDT Setup key is pressed. There are several types of softkeys available.

5-2

Figure 5-1

Agilent 54754A TDR/TDT Setup Menu

TDR/TDT Setup Stimulus

TDR/TDT help . . .

TDT 1 dest

Off

1 only

2 only

1 and 2

differential

common mode

external

Cancel

Enter

Single ended TDR/TDT

Differential common mode TDR/TDT

Done

channel 2

none

Cancel

Enter

TDT 2 dest

TDR 1 dest

channel 1

none

Cancel

Enter

channel 2

none

Cancel

Enter

5-3

Agilent 54754A TDR/TDT Setup Menu

Normalize response . . .

Normalize 1 response . . .

Normalize 2 response . . .

Risetime

TDR/TDT

TDR normalize

Establish normalization & ref plane

Done

Risetime

TDR/TDT

TDR normalize

Establish normalization & ref plane

Done

Risetime

TDR/TDT

TDR

TDT

off

on

TDR

TDT

off

on

TDR

TDT

5-4

TDR normalize

Establish normalization & ref plane

Done

off

on

TDR response 1 . . . Response off

differential

common mode

Cancel

Enter

Agilent 54754A TDR/TDT Setup Menu

Response scaling . . . Vertical

TDR response 2 . . . Response off

differential

common mode

Cancel

Enter

Response scaling . . . Vertical

Establish ref plane

Horizontal

Done

Horizontal

Done

track source

manual

track source

manual

track source

manual

track source

manual

Y Scale

Y Offset

X Scale

X Position

Y Scale

Y Offset

X Scale

X Position

5-5

Agilent 54754A TDR/TDT Setup Menu

TDR rate automatic . . . (250 kHz)

Preset TDR/TDT

TDR/TDT Setup Menu.

automatic

manual

Done

TDR rate

5-6

Table 5-1

Agilent 54754A TDR/TDT Setup Menu

Displaying the TDR/TDT Setup Menu

To display the TDR/TDT Setup menu, press the TDR/TDT Setup key on the TDR plug-in module.

Stimulus

Pressing the Stimulus softkey produces a pull-down menu used to turn on or turn off the TDR step. The differential TDR plug-in has two TDR channels. The following table contains a list of the available stimulus menu choices and their descriptions.

Stimulus Menu Choices

Stimulus Description

off Turns the TDR steps off for both TDR channels and the TDR

measurement system off.

1 only Turns the TDR step on for channel 1 only and enables the TDR

measurement system.

2 only Turns the TDR step on for channel 2 only and enables the TDR

measurement system.

1 and 2 Turns the TDR steps on for both channels. This mode is used to

make two independent single-ended TDR measurements.

differential Turns the differential TDR steps on for both channels . The step for

channel 1 is a positive going step while the step for channel 2 is effectively a negative going step. This mode is used to make differential TDR measurements

common mode Turns the common mode TDR steps on for both channels. Both

steps are positive going steps. Unlike the 1 and 2 mode, this mode is used to make common mode measurements.

external This setup provides control for and requires an external step

generator before measurements can be made.

Key Path TDR/TDT Setup Stimulus

5-7

Agilent 54754A TDR/TDT Setup Menu

TDT 1 dest

1 Only Stimulus Menus

This section describes the menus that are available when the stimulus is set to

1 only

TDT 1 dest

Pressing the TDT 1 dest softkey produces a pull-down menu used to select the channel used as the destination channel for TDT measurements. The choices available for this pull-down menu depend on the other TDR or electrical plugin, if any, in the mainframe.

Any electrical channel is potentially a valid TDT destination channel. The TDT destination may not be assigned to a channel already assigned as a TDT destination.

If no other valid TDT destination channels are available, then "none" is the only choice. If a TDT destination other than none is selected, then the Preset TDR/TDT control will turn on and preset the TDT destination channel.

.

Key Path TDR/TDT Setup TDT 1 dest

Normalize response . . .

The Normalize response function is available for all the Stimulus types except differential and common mode. The Normalize response function allows you to change the risetime of the normalized step, to select TDR and TDT normalization, to turn on or off the display of the normalized TDR or TDT trace, to change the scaling of the normalized trace, and to establish the normalization filter values and reference plane.

Risetime

The Risetime function allows you to change the normalized step’s risetime from a minimum of

10 ps

or

time per division (s/div) 10 divisions×

min 8 points

5-8

------------ ------------- ------------- ---------- ------------- ------------- ------------- ------

×=

record length

which ever is greater, to a maximum of

max 5 time per division (s/div)×=

While the TDR step’s risetime applied to the system under test is fixed, the measured response has a set of mathematical operations applied to it. These mathematical operations effectively change the displayed response to the system just as if a different TDR step risetime had actually been applied. This allows you to select a risetime for TDR/TDT measurements that is close to the actual risetime used in your system. This risetime value applies to both TDR and TDT normalized channels. For more information on normalization, see

Chapter 10, ”Improving Time Domain Network Measurements”.

Key Path TDR/TDT Setup Normalize response . . . Risetime

TDR/TDT

The TDR/TDT function is used to select between TDR and TDT for normalization. Both TDR and TDT channels can be normalized. This control selects which normalized trace is referred to for the following controls. Before TDT normalization can be done, you must select a TDT destination (TDT 1 dest).

Agilent 54754A TDR/TDT Setup Menu

Normalize response . . .

Key Path TDR/TDT Setup Normalize response . . . TDR/TDT

TDR or TDT normalize

The TDR normalize function is available if the TDR mode is selected by using the previous menu otherwise the TDT normalize function is available. In either case, this function turns on or off the display of the normalized trace. The TDR and TDT normalization functions can be on at the same time.

Key Path TDR/TDT Setup Normalize response . . . TDR normalize

Normalize scaling . . .

The Normalize scaling function is used when vertical and horizontal scaling of the normalized response is required that is independent from that of the source channel. This function only appears when TDR or TDT normalize is set to on.

Key Path TDR/TDT Setup Normalize response . . . Normalize scaling . . .

5-9

Agilent 54754A TDR/TDT Setup Menu

Normalize response . . .

Vertical There are two choices for vertical mode: track source and manual. The track source mode sets the control of the vertical scaling for the normalized trace to that of the source channel. When manual mode is selected, the Y Scale and Y Offset menus appear allowing you to independently change the vertical scale and offset of the normalized trace.

Key Path TDR/TDT Setup Normalize response . . .Normalize scaling . . . Vertical

Horizontal There are two choices for horizontal mode: track source and manual. The track source mode sets the control of the horizontal scaling

for the normalized trace to that of the source channel. When manual mode is selected, the Y Scale and Y Position menus appear allowing you to independently change the horizontal scale and position for the normalized trace.

Key Path TDR/TDT Setup Normalize response . . .Normalize scaling . . . Horizontal

Establish normalization & ref plane

The Establish normalization & ref plane function establishes the filter values used to normalize a channel and to set the reference plane for TDR and TDT measurements. This function must be performed separately for TDR and TDT modes. The normalization and reference plane must be re-established when power is lost or when the instrument is turned off. However, the values used for normalization and reference plane calculations can be stored to and re-loaded from disk. (See the Disk Menu chapter in the Agilent 83480A, Agilent 54750 User’s Guide for more information.)

The normalization filter values and reference plane are invalidated when the timebase scale, record length or channel bandwidth is changed. Also, the normalization process will not be able to remove small synchronous noise in the channels baseline if the timebase position is changed. For most measurements this error is very small.

The reference plane must be established before ohm, % reflect or gain units are selectable for the channel. Also, the Reference ref plane available in the Marker menu.

The function steps you through the normalization and reference plane procedure for the selected measurement type. The procedure steps are displayed at the top of the screen. The items required for calibration are shown in Table 5-2 on page 5-11.

5-10

function is not

Agilent 54754A TDR/TDT Setup Menu

TDR rate automatic . . . (250 kHz)

Table 5-2

Establish normalization & ref plane Hardware Requirements

Measurement Requirements

TDR 50 ohm 3.5 mm SMA terminator

3.5 mm SMA short

TDT 1 or 2 each 3.5 mm SMA cables

3.5 mm barrel connector

Key Path TDR/TDT Setup Normalize response . . . Establish normalization & ref plane . . .

TDR rate automatic . . . (250 kHz)

The TDR rate automatic . . . (250 kHz) function allows you to manually or automatically select the repetition rate of the TDR step. The range of values for manual mode selection are from 50 Hz to 250 kHz repetition rate using a 1-2-5 sequence. When this function is set to automatic, the TDR step repetition rate varies automatically as the Time base Scale is changed to keep multiple steps off screen. As the TDR rate decreases, TDR measurements can be made on longer transmission lines.

Key Path TDR/TDT Setup TDR rate automatic

Key Path TDR/TDT Setup TDR rate manual

5-11

Table 5-3

Agilent 54754A TDR/TDT Setup Menu

Preset TDR/TDT

The Preset TDR/TDT function prepares the oscilloscope for making TDR/TDT measurements by automatically setting several menu fields. The TDR preset feature appears in the TDR/TDT Setup menu once a stimulus has been selected. The menus that are affect by this feature are shown in Table 5-3.

Preset TDR/TDT Configuration

Menu Menu Item Set To

Acquisition Averaging on

Best Flatness

Time Base Scale 500.0 ps/div

Position Set to a value which places the

incident edge on screen.

Channel 1 Setup Display on

Scale 100 mV/div

Offset 200.0 mV

Bandwidth 12.4 GHz

Attenuation units ratio

Attenuation 1.000 : 1

Key Path TDR/TDT Setup Preset TDR/TDT

5-12

2 Only Stimulus Menus

This section describes the menus that are available when the stimulus is set to

2 only

TDT 2 dest

Pressing the TDT 2 dest softkey produces a pull-down menu used to select the channel used as the destination channel for TDT measurements. The choices available for this pull-down menu depend on the other TDR or electrical plugin, if any, in the mainframe.

Any electrical channel is potentially a valid TDT destination channel. The TDT destination may not be assigned to a channel already assigned as a TDT destination.

If no other valid TDT destination channels are available then "none" is the only choice. If a TDT destination other than none is selected then the preset TDR/ TDT control will turn on and preset the TDT destination channel.

Key Path TDR/TDT Setup TDT 2 dest

Normalize response . . .

.

The Normalize response function is available for all the Stimulus types except differential and common mode. The Normalize response function allows you to change the risetime of the normalized step, to select TDR and TDT normalization, to turn on or off the display of the normalized TDR or TDT trace, to change the scaling of the normalized trace, and to establish the normalization filter values and reference plane.

Risetime

The Risetime function allows you to change the normalized step’s risetime from a minimum of

10 ps

or

time per division (s/div) 10 divisions×

min 8 points

which ever is greater, to a maximum of

max 5 time per division (s/div)×=

While the TDR step’s risetime applied to the system under test is fixed, the measured response has a set of mathematical operations applied to it. These mathematical operations effectively change the displayed response to the

------------ ------------- ------------- ---------- ------------- ------------- ------------- ------

×=

record length

5-13

Agilent 54754A TDR/TDT Setup Menu

Normalize response . . .

system just as if a different TDR step risetime had actually been applied. This allows you to select a risetime for TDR/TDT measurements that is close to the actual risetime used in your system. This risetime value applies to both TDR and TDT normalized channels. For more information on normalization, see

Chapter 10, ”Improving Time Domain Network Measurements”.

Key Path TDR/TDT Setup Normalize response . . . Risetime

TDR/TDT

The TDR/TDT function is used to select between TDR and TDT for normalization. Both TDR and TDT channels can be normalized. This control selects which normalized trace is referred to for the following controls. Before TDT normalization can be done, you must select a TDT destination (TDT 2 dest).

Key Path TDR/TDT Setup Normalize response . . . TDR/TDT

TDR or TDT normalize

The TDR normalize function is available if the TDR mode is selected by using the previous menu otherwise the TDT normalize function is available. In either case, this function turns on or off the display of the normalized trace. The TDR and TDT normalization functions can be on at the same time.

Key Path TDR/TDT Setup Normalize response . . . TDR normalize

Normalize scaling . . .

The Normalize scaling function is used when vertical and horizontal scaling of the normalized response is required that is independent from that of the source channel. This function only appears when TDR or TDT normalize is set to on.

Key Path TDR/TDT Setup Normalize response . . . Normalize scaling . . .

Vertical There are two choices for vertical mode: track source and manual. The track source mode sets the control of the vertical scaling for the normalized trace to that of the source channel. When manual mode is selected, the Scale and Offset menus appear allowing you to independently change the vertical scale and offset of the normalized trace.

Key Path TDR/TDT Setup Normalize response . . .Normalize scaling . . . Vertical

Horizontal There are two choices for horizontal mode: track source and manual. The track source mode sets the control of the horizontal scaling

for the normalized trace to that of the source channel. When manual mode is selected, the Scale and Position menus appear allowing you to

5-14

Agilent 54754A TDR/TDT Setup Menu

Normalize response . . .

independently change the horizontal scale and position for the normalized trace.

Key Path TDR/TDT Setup Normalize response . . .Normalize scaling . . . Horizontal

Establish normalization & ref plane

The Establish normalization & ref plane function establishes the filter values used to normalize a channel and to set the reference plane for TDR and TDT measurements. This function must be performed separately for TDR and TDT modes. The normalization and reference plane must be re-established when power is lost or when the instrument is turned off. However, the values used for normalization and reference plane calculations can be stored to and re-loaded from disk. (See the Disk Menu chapter in the Agilent 83480A, Agilent 54750 User’s Guide for more information.)

The normalization filter values and reference plane are invalidate when the timebase scale, record length or channel bandwidth is changed. Also, the normalization process will not be able to remove small synchronous noise in the channels baseline if the timebase position is changed. For most measurements this error is very small.

The reference plane must be established before ohm, % reflect or gain units are selectable for the channel. Also, the Reference ref plane available in the Marker menu.

function is not

5-15

Agilent 54754A TDR/TDT Setup Menu

TDR rate automatic . . . (250 kHz)

The function steps you through the normalization and reference plane procedure for the selected measurement type. The procedure steps are displayed at the top of the screen. The items required for calibration are shown in Tabl e 5-4 .

Table 5-4

Establish normalization & ref plane Hardware Requirements

Measurement Requirements

TDR 50 ohm 3.5 mm SMA terminator

3.5 mm SMA short

TDT 1 or 2 each 3.5 mm SMA cables

3.5 mm barrel connector

Key Path TDR/TDT Setup Normalize response . . . Establish normalization & ref plane . . .

TDR rate automatic . . . (250 kHz)

The TDR rate automatic . . . (250 kHz) function allows you to manually or automatically select the repetition rate of the TDR step. The range of values for manual mode selection are from 50 Hz to 250 kHz repetition rate using a 1-2-5 sequence. When this function is set to automatic, the TDR step repetition rate varies automatically as the Time base Scale is changed to keep multiple steps off screen. As the TDR rate decreases, TDR measurements can be made on longer transmission lines.

Key Path TDR/TDT Setup TDR rate automatic

Key Path TDR/TDT Setup TDR rate manual

5-16

Table 5-5

Agilent 54754A TDR/TDT Setup Menu

Preset TDR/TDT

The Preset TDR/TDT function prepares the oscilloscope for making TDR/TDT measurements by automatically setting several menu fields. The TDR preset feature appears in the TDR/TDT Setup menu once a stimulus has been selected. The menus that are affect by this feature are shown in Table 5 -5.

Preset TDR/TDT Configuration

Menu Menu Item Set To

Acquisition Averaging on

Best Flatness

Time Base Scale 500.0 ps/div

Position Set to a value which places the

incident edge on screen.

Channel 2 Setup Display on

Scale 100 mV/div

Offset 200.0 mV

Bandwidth 12.4 GHz

Attenuation units ratio

Attenuation 1.000 : 1

Key Path TDR/TDT Setup Preset TDR/TDT

5-17

1 and 2 Stimulus Menus

This section describes the menus that are available when the stimulus is set to

1 and 2

TDT 1 dest

Pressing the TDT 1 dest softkey produces a pull-down menu used to select the channel used as the destination channel for channel 1 TDT measurements. The choices available for this pull-down menu depend on the other TDR or electrical plug-in, if any, in the mainframe.

Any electrical channel is potentially a valid TDT destination channel. The TDT destination may not be assigned to a channel already assigned as a TDT destination.

If no other valid TDT destination channels are available then "none" is the only choice. If a TDT destination other than none is selected then the preset TDR/ TDT control will turn on and preset the TDT destination channel.

Key Path TDR/TDT Setup TDT 1 dest

TDT 2 dest

.

Pressing the TDT 2 dest softkey produces a pull-down menu used to select the channel used as the destination channel for channel 2 TDT measurements. The choices available for this pull-down menu depend on the other TDR or electrical plug-in, if any, in the mainframe.

Any electrical channel is potentially a valid TDT destination channel. The TDT destination may not be assigned to a channel already assigned as a TDT destination.

If no other valid TDT destination channels are available then "none" is the only choice. If a TDT destination other than none is selected then the preset TDR/ TDT control will turn on and preset the TDT destination channel.

Key Path TDR/TDT Setup TDT 2 dest

5-18

Agilent 54754A TDR/TDT Setup Menu

Normalize 1 response . . . Normalize 2 response . . .

When the Stimulus is 1 and 2, there are two menus, Normalize 1 response and Normalize 2 response, which are used to normalize the two independent TDR

channels separately. The functions allow you to change the risetime of the normalized step, to select TDR and TDT normalization, to turn on or off the display of the normalized TDR or TDT trace, to change the scaling of the normalized trace, and to establish the normalization filter values and reference plane.

Risetime

The Risetime function allows you to change the normalized step’s risetime from a minimum of

10 ps

or

time per division (s/div) 10 divisions×

min 8 points

which ever is greater, to a maximum of

max 5 time per division (s/div)×=

------------ ------------- ------------- ---------- ------------- ------------- ------------- ------

×=

record length

While the TDR step’s risetime applied to the system under test is fixed, the measured response has a set of mathematical operations applied to it. These mathematical operations effectively change the displayed response to the system just as if a different TDR step risetime had actually been applied. This allows you to select a risetime for TDR/TDT measurements that is close to the actual risetime used in your system. This risetime value applies to both TDR and TDT normalized channels. For more information on normalization, see

Chapter 10, ”Improving Time Domain Network Measurements”.

Key Path TDR/TDT Setup Normalize response . . . Risetime

TDR/TDT

The TDR/TDT function is used to select between TDR and TDT for normalization. Both TDR and TDT channels can be normalized. This control selects which normalized trace is referred to for the following controls. Before TDT normalization can be done, you must select a TDT destination (TDT 1 dest).

Key Path TDR/TDT Setup Normalize response . . . TDR/TDT

5-19

Agilent 54754A TDR/TDT Setup Menu

Normalize 1 response . . . Normalize 2 response . . .

TDR or TDT normalize

The TDR normalize function is available if the TDR mode is selected by using the previous menu otherwise the TDT normalize function is available. In either case, this function turns on or off the display of the normalized trace. The TDR and TDT normalization functions can be on at the same time.

Key Path TDR/TDT Setup Normalize response . . . TDR normalize

Normalize scaling . . .

The Normalize scaling function is used when vertical and horizontal scaling of the normalized response is required that is independent from that of the source channel. This function only appears when TDR or TDT normalize is set to on.

Key Path TDR/TDT Setup Normalize response . . . Normalize scaling . . .

Vertical There are two choices for vertical mode: track source and manual. The track source mode sets the control of the vertical scaling for the normalized trace to that of the source channel. When manual mode is selected, the Scale and Offset menus appear allowing you to independently change the vertical scale and offset of the normalized trace.

Key Path TDR/TDT Setup Normalize response . . .Normalize scaling . . . Vertical

Horizontal There are two choices for horizontal mode: track source and manual. The track source mode sets the control of the horizontal scaling

for the normalized trace to that of the source channel. When manual mode is selected, the Scale and Position menus appear allowing you to independently change the horizontal scale and position for the normalized trace.

Key Path TDR/TDT Setup Normalize response . . .Normalize scaling . . . Horizontal

Establish normalization & ref plane

The Establish normalization & ref plane function establishes the filter values used to normalize a channel and to set the reference plane for TDR and TDT measurements. This function must be performed separately for TDR and TDT modes. The normalization and reference plane must be re-established when power is lost or when the instrument is turned off. However, the values used for

5-20

Agilent 54754A TDR/TDT Setup Menu

TDR rate automatic . . . (250 kHz)

normalization and reference plane calculations can be stored to and re-loaded from disk. (See the Disk Menu chapter in the Agilent 83480A, Agilent 54750 User’s Guide for more information.)

The normalization filter values and reference plane are invalidate when the timebase scale, record length or channel bandwidth is changed. Also, the normalization process will not be able to remove small synchronous noise in the channels baseline if the timebase position is changed. For most measurements this error is very small..

The reference plane must be established before ohm, % reflect or gain units are selectable for the channel. Also, the Reference ref plane

function is not

available in the Marker menu.

The function steps you through the normalization and reference plane procedure for the selected measurement type. The procedure steps are displayed at the top of the screen. The items required for calibration are shown in Tabl e 5-6 .

Table 5-6

Establish normalization & ref plane Hardware Requirements

Measurement Requirements

TDR 50 ohm 3.5 mm SMA terminator

3.5 mm SMA short

TDT 1 or 2 each 3.5 mm SMA cables

3.5 mm barrel connector

Key Path TDR/TDT Setup Normalize response . . . Establish normalization & ref plane . . .

TDR rate automatic . . . (250 kHz)

The TDR rate automatic . . . (250 kHz) function allows you to manually or automatically select the repetition rate of the TDR step. The range of values for manual mode selection are from 50 Hz to 250 kHz repetition rate using a 1-2-5 sequence. When this function is set to automatic, the TDR step repetition

5-21

Agilent 54754A TDR/TDT Setup Menu

Preset TDR/TDT

rate varies automatically as the Time base Scale is changed to keep multiple steps off screen. As the TDR rate decreases, TDR measurements can be made on longer transmission lines.

Key Path TDR/TDT Setup TDR rate automatic

Key Path TDR/TDT Setup TDR rate manual

Preset TDR/TDT

The Preset TDR/TDT function prepares the oscilloscope for making TDR/TDT measurements by automatically setting several menu fields. The TDR preset feature appears in the TDR/TDT Setup menu once a stimulus has been selected. The menus that are affect by this feature are shown in Table 5-7.

Table 5-7

Preset TDR/TDT Configuration

Menu Menu Item Set To

Acquisition Averaging on

Best Flatness

Time Base Scale 500.0 ps/div

Position Set to a value which places the

Channel 1 Setup and Display on

Channel 2 Setup Scale 100 mV/div

Offset 200.0 mV

Bandwidth 12.4 GHz

Attenuation units ratio

Attenuation 1.000 : 1

incident edge on screen.

Key Path TDR/TDT Setup Preset TDR/TDT

5-22

Differential and Common Mode Stimulus Menus

This section describes the menus that are available when the stimulus is set to

differential

TDR/TDT

This TDR/TDT function allows you to select either TDR measurements or TDT measurements. The TDT measurement capability requires that an additional TDR or electrical plug-in module be installed in the mainframe.

Key Path TDR/TDT Setup TDR/TDT

TDR response 1

The TDR response 1 function is used to enable or disable the display of the differential or common mode TDR response 1. The choices available are off, differential, or common mode.

Key Path TDR/TDT Setup TDR response 1

or common mode.

Response scaling . . .

The Response scaling function is used when vertical and horizontal scaling of the normalized response is required that is independent from that of the source channel. This function only appears when TDR response 1 is set to differential or common mode.

Key Path TDR/TDT Setup TDR response 1 Response scaling . . .

Vertical There are two choices for vertical mode: track source and manual. The track source mode sets the control of the vertical scaling for the normalized trace to that of the source channel. When manual mode is selected, the Scale and Offset menus appear allowing you to independently change the vertical scale and offset of the normalized trace.

Key Path TDR/TDT Setup TDR response 1 . . .Response scaling . . . Vertical

5-23

Agilent 54754A TDR/TDT Setup Menu

TDR response 2

Horizontal There are two choices for horizontal mode: track source and manual. The track source mode sets the control of the horizontal scaling

for the normalized trace to that of the source channel. When manual mode is selected, the Scale and Position menus appear allowing you to independently change the horizontal scale and position for the normalized trace.

Key Path TDR/TDT Setup TDR response 1 . . .Response scaling . . . Horizontal

TDR response 2

The TDR response 2 function is used to enable or disable the display of the differential or common mode TDT response 2. The choices available are off, differential, or common mode.

Key Path TDR/TDT Setup TDR response 2

Response scaling . . .

The Response scaling function is used when vertical and horizontal scaling of the normalized response is required that is independent from that of the source channel. This function only appears when TDR response 2 is set to differential or common mode.

Key Path TDR/TDT Setup TDR response 2 Response scaling . . .

Vertical There are two choices for vertical mode: track source and manual. The track source mode sets the control of the vertical scaling for the normalized trace to that of the source channel. When manual mode is selected, the Scale and Offset menus appear allowing you to independently change the vertical scale and offset of the normalized trace.

Key Path TDR/TDT Setup TDR response 2 . . .Response scaling . . . Vertical

Horizontal There are two choices for horizontal mode: track source and manual. The track source mode sets the control of the horizontal scaling

for the normalized trace to that of the source channel. When manual mode is selected, the Scale and Position menus appear allowing you to independently change the horizontal scale and position for the normalized trace.

Key Path TDR/TDT Setup TDR response 2 . . .Response scaling . . . Horizontal

5-24

Agilent 54754A TDR/TDT Setup Menu

TDT response 1

The TDT response 1 function is used to enable or disable the display of the differential or common mode response 1. The choices available are off, differential, or common mode.

Key Path TDR/TDT Setup TDT response 1

Response scaling . . .

The Response scaling function is used when vertical and horizontal scaling of the normalized response is required that is independent from that of the source channel. This function only appears when TDT response 1 is set to differential or common mode.

Key Path TDR/TDT Setup TDT response 1 Response scaling . . .

Vertical There are two choices for vertical mode: track source and manual. The track source mode sets the control of the vertical scaling for the normalized trace to that of the source channel. When manual mode is selected, the Scale and Offset menus appear allowing you to independently change the vertical scale and offset of the normalized trace.

TDT response 1

Key Path TDR/TDT Setup TDT response 1 . . .Response scaling . . . Vertical

Horizontal There are two choices for horizontal mode: track source and manual. The track source mode sets the control of the horizontal scaling

for the normalized trace to that of the source channel. When manual mode is selected, the Scale and Position menus appear allowing you to independently change the horizontal scale and position for the normalized trace.

Key Path TDR/TDT Setup TDT response 1 . . .Response scaling . . . Horizontal

TDT response 2

The TDT response 2 function is used to enable or disable the display of the differential or common mode response 2. The choices available are off, differential, or common mode.

Key Path TDR/TDT Setup TDT response 2

5-25

Agilent 54754A TDR/TDT Setup Menu

Establish ref plane

Response scaling . . .

The Response scaling function is used when vertical and horizontal scaling of the normalized response is required that is independent from that of the source channel. This function only appears when TDT response 2 is set to differential or common mode.

Key Path TDR/TDT Setup TDT response 2 Response scaling . . .

Vertical There are two choices for vertical mode: track source and manual. The track source mode sets the control of the vertical scaling for the normalized trace to that of the source channel. When manual mode is selected, the Scale and Offset menus appear allowing you to independently change the vertical scale and offset of the normalized trace.

Key Path TDR/TDT Setup TDT response 2 . . .Response scaling . . . Vertical

Horizontal There are two choices for horizontal mode: track source and manual. The track source mode sets the control of the horizontal scaling

for the normalized trace to that of the source channel. When manual mode is selected, the Scale and Position menus appear allowing you to independently change the horizontal scale and position for the normalized trace.

Key Path TDR/TDT Setup TDT response 2 . . .Response scaling . . . Horizontal

Establish ref plane

The Establish ref plane function is used to set the reference plane for TDR and TDT measurements for differential or common mode stimulus. The function steps you through the calibration procedure for the selected measurement type. The steps are displayed at the top of the screen. The items required for calibration are shown in Table 5-8 on page 5-27.

5-26

Table 5-8

Agilent 54754A TDR/TDT Setup Menu

TDR rate automatic . . . (250 kHz)

Establish ref plane Hardware Requirements

Measurement Requirements

TDR 50 ohm 3.5 mm SMA terminator

3.5 mm SMA short

TDT 1 or 2 each 3.5 mm SMA cables

3.5 mm barrel connector

The reference plane is invalidated when the timebase scale, record length or channel bandwidth is changed.

Before establishing a reference plane for common mode and differential TDR, the test setup must be deskewed. See Chapter 8, ”Differential TDR

Measurements” for information on how to deskew a test setup.

The reference plane must be established before ohm, % reflect or gain units are selectable for the channel. Also, the Reference ref plane available in the Marker menu.

Key Path TDR/TDT Setup Normalize response . . . Establish ref plane . . .

TDR rate automatic . . . (250 kHz)

The TDR rate automatic . . . (250 kHz) function allows you to manually or automatically select the repetition rate of the TDR step. The range of values for manual mode selection are from 50 Hz to 250 kHz repetition rate using a 1-2-5 sequence. When this function is set to automatic, the TDR step repetition rate varies automatically as the Time base Scale is changed to keep multiple steps off screen. As the TDR rate decreases, TDR measurements can be made on longer transmission lines.

Key Path TDR/TDT Setup TDR rate automatic

Key Path TDR/TDT Setup TDR rate manual

function is not

5-27

Table 5-9

Agilent 54754A TDR/TDT Setup Menu

Preset TDR/TDT

The Preset TDR/TDT function prepares the oscilloscope for making TDR/TDT measurements by automatically setting several menu fields. The TDR preset feature appears in the TDR/TDT Setup menu once a stimulus has been selected. The menus that are affect by this feature are shown in Table 5-9 and Table 5-10.

Differential Stimulus Preset TDR/TDT Configuration

Menu Menu Item Set To

Acquisition Averaging on

Best Flatness

Time Base Scale 500.0 ps/div

Position Set to a value which places the

incident edge on screen.

Channel 1 Setup Display on

Scale 100 mV/div

Offset 200.0 mV

Bandwidth 12.4 GHz

Attenuation units ratio

Attenuation 1.000 : 1

Channel 2 Setup Scale 100 mV/div

Offset -200 mV

5-28

Table 5-10

Agilent 54754A TDR/TDT Setup Menu

Preset TDR/TDT

Common Mode Stimulus Preset TDR/TDT Configuration

Menu Menu Item Set To

Acquisition Averaging on

Best Flatness

Time Base Scale 500.0 ps/div

Position Set to a value which places the

incident edge on screen.

Channel 1 Setup Display on

Scale 100 mV/div

Offset 200.0 mV

Bandwidth 12.4 GHz (for Stimulus on)

18.0 GHz (for Stimulus external)

Attenuation units ratio

Attenuation 1.000 : 1

Channel 2 Setup Scale 100 mV/div

Offset 200.0 mV

Key Path TDR/TDT Setup Preset TDR/TDT

5-29

External Stimulus Menus

This section describes the menus that are available when the stimulus is set to

external

TDT 1 dest

Pressing the TDT 1 dest softkey produces a pull-down menu used to select the channel used as the destination channel for TDT measurements. The choices available for this pull-down menu depend on the other TDR or electrical plugin, if any, in the mainframe.

Any electrical channel is potentially a valid TDT destination channel. The TDT destination may not be assigned to a channel already assigned as a TDT destination. The TDT destination may not be set to the currently defined TDR destination channel.

If no other valid TDT destination channels are available then "none" is the only choice. If a TDT destination other than none is selected then the preset TDR/ TDT control will turn on and preset the TDT destination channel.

Key Path TDR/TDT Setup TDT 1 dest

TDR 1 dest

.

Pressing the TDR 1 dest softkey produces a pull-down menu used to select the channel used as the destination channel for TDR measurements. Any electrical channel is a valid TDR destination channel. The TDR destination may not be set to the currently defined TDT destination.

Key Path TDR/TDT Setup TDR 1 dest

5-30

Agilent 54754A TDR/TDT Setup Menu

Normalize response . . .

The Normalize response function allows you to change the risetime of the normalized step, to select TDR and TDT normalization, to turn on or off the display of the normalized TDR or TDT trace, to change the scaling of the normalized trace, and to establish the normalization filter values and reference plane.

Risetime

The Risetime function allows you to change the normalized step’s risetime from a minimum of

10 ps

or

time per division (s/div) 10 divisions×

min 8 points

which ever is greater, to a maximum of

max 5 time per division (s/div)×=

------------ ------------- ------------- ---------- ------------- ------------- ------------- ------

×=

record length

While the TDR step’s risetime applied to the system under test is fixed, the measured response has a set of mathematical operations applied to it that effectively displays the response to the system as if a different TDR step risetime had actually been applied. This allows you to select a risetime for TDR/TDT measurements that is close to the actual risetime used in your system. This risetime value applies to both TDR and TDT normalized channels. For more information on normalization, see Chapter 10, ”Improving Time Domain

Network Measurements”.

Key Path TDR/TDT Setup Normalize response . . . Risetime

TDR/TDT

The TDR/TDT function is used to select between TDR and TDT for normalization. Both TDR and TDT channels can be normalized. This control selects which normalized trace is referred to for the following controls. Before TDT normalization can be done, you must select a TDT destination (TDT 1 dest).

Key Path TDR/TDT Setup Normalize response . . . TDR/TDT

5-31

Agilent 54754A TDR/TDT Setup Menu

Normalize response . . .

TDR or TDT normalize

The TDR normalize function is available if the TDR mode is selected by using the previous menu otherwise the TDT normalize function is available. In either case, this function turns on or off the display of the normalized trace. The TDR and TDT normalization functions can be on at the same time.

Key Path TDR/TDT Setup Normalize response . . . TDR normalize

Normalize scaling . . .

The Normalize scaling function is used when vertical and horizontal scaling of the normalized response is required that is independent from that of the source channel. This function only appears when TDR or TDT normalize is set to on.

Key Path TDR/TDT Setup Normalize response . . . Normalize scaling . . .

Vertical There are two choices for vertical mode: track source and manual. The track source mode sets the control of the vertical scaling for the normalized trace to that of the source channel. When manual mode is selected, the Scale and Offset menus appear allowing you to independently change the vertical scale and offset of the normalized trace.

Key Path TDR/TDT Setup Normalize response . . .Normalize scaling . . . Vertical

Horizontal There are two choices for horizontal mode: track source and manual. The track source mode sets the control of the horizontal scaling

for the normalized trace to that of the source channel. When manual mode is selected, the Scale and Position menus appear allowing you to independently change the horizontal scale and position for the normalized trace.

Key Path TDR/TDT Setup Normalize response . . .Normalize scaling . . . Horizontal

Establish normalization & ref plane

The Establish normalization & ref plane function establishes the filter values used to normalize a channel and to set the reference plane for TDR and TDT measurements. This function must be performed separately for TDR and TDT modes. The normalization and reference plane must be re-established when power is lost or when the instrument is turned off. However, the values used for

5-32

Agilent 54754A TDR/TDT Setup Menu

Normalize response . . .

normalization and reference plane calculations can be stored to and re-loaded from disk. (See the Disk Menu chapter in the Agilent 83480A, Agilent 54750 User’s Guide for more information.)

The normalization filter values and reference plane are invalidate when the timebase scale, record length or channel bandwidth is changed. Also, the normalization process will not be able to fully remove step non-flatness if the timebase position is changed since the filter values have been established.

The reference plane must be established before ohm, % reflect or gain units are selectable for the channel. Also, the Reference ref plane

function is not

available in the Marker menu.

The function steps you through the normalization and reference plane procedure for the selected measurement type. The procedure steps are displayed at the top of the screen. The items required for calibration are shown in Table 5-11.

Table 5-11

Establish normalization & ref plane Hardware Requirements

Measurement Requirements

TDR 50 ohm 3.5 mm SMA terminator

3.5 mm SMA short

TDT 1 or 2 each 3.5 mm SMA cables

3.5 mm barrel connector

Key Path TDR/TDT Setup Normalize response . . . Establish normalization & ref plane . . .

5-33

Agilent 54754A TDR/TDT Setup Menu

TDR rate automatic . . . (250 kHz)

The TDR rate automatic . . . (250 kHz) function allows you to manually or automatically select the repetition rate of the TDR step. The range of values for manual mode selection are from 50 Hz to 250 kHz repetition rate using a 1-2-5 sequence. When this function is set to automatic, the TDR step repetition rate varies automatically as the Time base Scale is changed to keep multiple steps off screen. As the TDR rate decreases, TDR measurements can be made on longer transmission lines.

Key Path TDR/TDT Setup TDR rate automatic

Key Path TDR/TDT Setup TDR rate manual

Preset TDR/TDT

The Preset TDR/TDT function prepares the oscilloscope for making TDR/TDT measurements by automatically setting several menu fields. The TDR preset feature appears in the TDR/TDT Setup menu once a stimulus has been selected. The menus that are affect by this feature are shown in Table 5-12.

Table 5-12

Preset TDR/TDT Configuration

Menu Menu Item Set To

Acquisition Averaging on

Best Flatness

Time Base Scale 500.0 ps/div

Position Set to a value which places the incident

Channel 1 Setup Display on

Scale 100 mV/div

Offset 0.0 mV

Bandwidth 18.0 GHz

Attenuation units ratio

Attenuation 1.000 : 1

edge on screen.

Key Path TDR/TDT Setup Preset TDR/TDT

5-34

6

Measure and Other TDR Specific Menus

What you’ll find in this chapter

This chapter describes the Measure menu and the mainframe menu changes that occur when a TDR plug-in module is in the mainframe.

CAUTION

The input circuits can be damaged by electrostatic discharge (ESD). Therefore, avoid appl ying static discharges to the front-pane l input connectors. Before connecting any coaxial cable to the connectors, momentarily short the center and outer conductors of the cable together. Avoid touching the frontpanel input connectors without first touching the frame of the instrument. Be sure the instrument is properly earth-grounded to prevent buildup of static charge.

There are several mainframe menus which change when a TDR plug-in module is inserted into the mainframe menus. This chapter will cover only the changes that occur to the mainframe menus and will not discuss the menu functions which are already documented in the Agilent 83480A, 54750A User’s Guide.

6-2

Figure 6-1

Measure and Other TDR Specific Menus

Blue Key TDR/TDT Measure TDR minimum reflection

TDR maximum reflection

TDT propagation delay

TDT gain

channel #

response #

Cancel

Enter

channel #

response #

Cancel

Enter

channel #

response #

Cancel

Enter

channel #

response #

Cancel

Enter

TDR Setup menu.

6-3

Measure and Other TDR Specific Menus

TDR/TDT Measure Menu

To display the Measure menu, press the blue key immediately followed by the TDR/TDT Measure key on the TDR plug-in module. There are four automated

measurements which may be selected: TDR minimum reflection, TDR maximum reflection, TDT propagation delay, and TDT gain.

TDR Minimum Reflection

Pressing the TDR minimum reflection softkey display the automatically calculated minimum percent reflection value at the bottom of the display under the waveform graticule.

The TDR plug-in module must be calibrated and a reference plane established before this measurement can be selected.

The calculation of the value is dependant on the type of response and stimulus that are selected.

For differential response to differential stimulus and common mode response to common mode stimulus, the following formula is used:

Minimum reflection 100

where:

V

= the minimum voltage value along the waveform

min

V

1ref50Ω

V

= the channel 1 reference plane voltage into a short

1ref0Ω

V

2ref50Ω

V

= the channel 2 reference plane voltage into a short

2ref0Ω

6-4

=

V

()

1

50

ref

V

------------- ------------- ------------- ---------- ------------- ------------- ------------- ------------ ---------

V

–

()

1

ref

V

1

0

Ω

ref

Ω

min

–

V

+

50

2

Ω

+

()

50

Ω

ref

V

2

ref

V

–

50

2

ref

0

Ω

= the channel 1 reference plane voltage into a 50 ohm load

= the channel 2 reference plane voltage into a 50 ohm load

Measure and Other TDR Specific Menus

TDR/TDT Measure Menu

For differential response to common mode stimulus and common mode response to differential stimulus, the following formula is used.

Minimum reflection 100

=

V

----------- ------------- ------------- ---------- ------------- -----------

------------ ------------- ------------- ---------- ------------- ------------- ------------- ------------ ----------

V

()

1

50

ref

------------- ------------- ------------- ---------- ------------- ------------- ------------- ------------ ---------

V

–

()

1

50

min

ref

2

V

–

Ω

+

1

0

Ω

ref

2

where:

V

= the minimum voltage value along the waveform

min

V

= the channel 1 reference plane voltage into a 50 ohm load

1ref50Ω

= the channel 1 reference plane voltage into a short

1ref0Ω

= the channel 2 reference plane voltage into a 50 ohm load

2ref50Ω

= the channel 2 reference plane voltage into a short

2ref0Ω

For all other stimulus, the following formula is used.

V

–

50

Minimum reflection 100

=

minVref



------------ ------------- ------------ ----



V

50

ref

Ω

V

–

0

Ω

ref

Ω

where:

V

= the minimum voltage value along the waveform

min

V

= the reference plane voltage into a 50 ohm load

ref50 Ω

V

= the reference plane voltage into a short

ref0Ω

Key Path blue key TDR/TDT Measure TDR minimum reflection

V

+

2

Ω

()

50

Ω

ref

V

2

ref

V

–

50

2

ref

0

Ω

6-5

Measure and Other TDR Specific Menus

TDR/TDT Measure Menu

TDR Maximum Reflection

Pressing the TDR maximum reflection softkey display the automatically calculated maximum percent reflection value at the bottom of the display under the waveform graticule.

The TDR plug-in module must be calibrated and a reference plane established before this measurement can be selected.

The calculated value is dependant on the type of response and stimulus that are selected.

For differential response to differential stimulus and common mode response to common mode stimulus, the following formula is used:

Maximum reflection 100

=

V

------------- ------------ ------------- ----------- ------------- ------------ ------------- ------------- ---------

V

()

1

50

ref

V

–

()

1

ref

V

1

0

Ω

ref

Ω

max

–

V

+

50

2

Ω

+

()

50

Ω

ref

V

2

ref

V

–

50

2

ref

0

Ω

where:

= the maximum voltage value along the waveform

V

max

V

= the channel 1 reference plane voltage into a 50 ohm load

1ref50Ω

= the channel 1 reference plane voltage into a short

1ref0Ω

= the channel 2 reference plane voltage into a 50 ohm load

2ref50Ω

= the channel 2 reference plane voltage into a short

2ref0Ω

For differential response to common mode stimulus and common mode response to differential stimulus, the following formula is used.

Maximum reflection 100

=

V

------------- ------------ ------------- ----------- ------------ -----------

------------ ------------ ------------- ----------- ------------- ------------ ------------- ------------- ----------

V

()

1

50

ref

------------- ------------ ------------- ----------- ------------- ------------ ------------- ------------- ---------

V

–

()

1

max

ref

V

+

50

2

ref

50

Ω

2

V

–

1

Ω

ref

V

+

()

0

2

Ω

ref

V

–

50

2

ref

0

Ω

2

where:

V

= the maximum voltage value along the waveform

max

V

= the channel 1 reference plane voltage into a 50 ohm load

1ref50Ω

= the channel 1 reference plane voltage into a short

1ref0Ω

= the channel 2 reference plane voltage into a 50 ohm load

2ref50Ω

= the channel 2 reference plane voltage into a short

2ref0Ω

6-6