Agilent Technologies J-BERT N4903 User manual

S
Agilent J-BERT N4903
High-Performance Serial
BERT
User Guide
sAgilent Technologies

© Agilent Technologies, Inc. 2014
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Manual Part Number
N4903-91020
Edition
Release edition, December 2014
Printed in Germany
Agilent Technologies, Deutschland GmbH
Herrenberger Str. 130
71034 Böblingen, Germany
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CAUTION
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Contents
1 Planning the Test
Planning the Test - Concepts 9
Introduction to the Serial BERT 9
Introduction to the Serial BERT - Concepts 9
Which Test is Appropriate? 13
Which Test is Appropriate? - Concepts 13
Connecting the DUT 17
Connecting the DUT - Concepts 17
2 Setting up Patterns
Setting up Patterns - Concepts 23
User Patterns 27
User Patterns - Concepts 27
User Patterns - Procedures 38
User Patterns - Reference 43
Software-Generated PRBS 51
Software-Generated PRBS - Concepts 51
Software-Generated PRBS - Procedures 53
Software-Generated PRBS - Reference 53
Hardware-Generated PRBS 54
Hardware-Generated PRBS - Concepts 54
Hardware-Generated PRBS - Procedures 56
Hardware-Generated PRBS - Reference 56
User-Defined Sequences 56
User-Defined Sequences - Concepts 56
User-Defined Sequences - Procedures 59
User-Defined Sequences - Reference 61
3 Setting up the Pattern Generator
Setting up the Pattern Generator - Concepts 69
Agilent J-BERT N4903 High-Performance Serial BERT 3

Input and Output Ports 70
Input and Output Ports - Concepts 70
Input and Output Ports - Procedures 79
Input and Output Ports - Reference 82
Bit Rate 87
Bit Rate - Concepts 87
Bit Rate - Procedures 90
Bit Rate - Reference 91
Trigger Output 93
Trigger Output - Concepts 93
Trigger Output - Procedures 94
Trigger Output - Reference 94
Delay Control Input 97
Delay Control Input - Concepts 97
Delay Control Input - Procedures 98
Delay Control Input - Reference 99
Error Addition/Insertion 99
Error Addition/Insertion - Concepts 99
Error Addition/Insertion - Procedures 99
Error Addition/Insertion - Reference 101
Pattern Alternation 102
Pattern Alternation - Concepts 102
Pattern Alternation - Procedures 104
Pattern Alternation - Reference 106
4 Setting up the Error Detector
Setting up the Error Detector - Concepts 109
Inputs and Outputs 110
Inputs and Outputs - Concepts 110
Inputs and Outputs - Procedures 114
Data Input Setup - Reference 114
Clock Setup 116
Clock Setup - Concepts 116
Clock Setup - Procedures 121
Clock Setup - Reference 122
Sampling Point Setup 126
Sampling Point Setup - Concepts 126
Sampling Point Setup - Procedures 129
Sampling Point Setup - Reference 131
4 Agilent J-BERT N4903 High-Performance Serial BERT

Trigger and Aux Output 136
Trigger and Aux Output - Concepts 136
Trigger and Aux Output - Procedures 137
Trigger and Aux Output - Reference 137
Pattern Synchronization 138
Pattern Synchronization - Concepts 138
Pattern Synchronization - Procedures 150
Pattern Synchronization - Reference 151
Error Accumulation 151
Error Accumulation - Concepts 151
Error Accumulation - Procedures 152
Error Accumulation - Reference 152
BER Location 154
BER Location - Concepts 154
BER Location - Procedures 155
BER Location - Reference 155
Audio Signals 156
Audio Signals - Concepts 156
Audio Signals - Procedures 156
Audio Signals - Reference 157
5 Advanced Analysis
Advanced Analysis - Concepts 159
Advanced Analysis - Procedures 161
Advanced Analysis - Reference 166
DUT Output Timing/Jitter 173
DUT Output Timing/Jitter - Concepts 173
DUT Output Timing/Jitter - Procedures 182
DUT Output Timing/Jitter - Reference 184
Output Levels 195
Output Levels - Concepts 195
Output Levels - Procedures 198
Output Levels - Reference 203
Eye Opening 220
Eye Opening - Concepts 220
Eye Opening - Procedures 223
Eye Opening - Reference 229
Agilent J-BERT N4903 High-Performance Serial BERT 5

Error Location Capture 236
Error Location Capture - Concepts 236
Error Location Capture - Procedures 238
Error Location Capture - Reference 239
Fast Eye Mask 241
Fast Eye Mask - Concepts 241
Fast Eye Mask - Procedures 244
Fast Eye Mask - Reference 246
Eye Diagram 249
Eye Diagram - Concepts 249
Eye Diagram - Procedures 254
Eye Diagram - Reference 267
Spectral Jitter 278
Spectral Jitter - Concepts 278
Spectral Jitter - Procedures 286
Spectral Jitter - Reference 289
6 Evaluating Results
Evaluating Results - Concepts 297
Instantaneous Measurements 297
Instantaneous Measurements - Concepts 297
Instantaneous Measurements - Procedures 298
Instantaneous Measurements - Reference 300
Accumulated Measurements 302
Accumulated Measurements - Concepts 302
Accumulated Measurements - Procedures 303
Accumulated Measurements - Reference 304
Eye Measurements 310
Eye Measurements - Concepts 310
Eye Measurements - Procedures 311
Eye Measurements - Reference 311
7 Jitter Tolerance Tests
Jitter Tolerance Tests - Concepts 315
Jitter Setup 325
Jitter Setup - Concepts 325
Jitter Setup - Procedures 326
Jitter Setup - Reference 328
6 Agilent J-BERT N4903 High-Performance Serial BERT

Interference Channel Setup 336
Interference Channel Setup - Concepts 336
Interference Channel Setup - Procedures 336
Interference Channel Setup - Reference 337
Jitter Tolerance Characterization 338
Jitter Tolerance Characterization - Concepts 338
Jitter Tolerance Characterization - Procedures 343
Jitter Tolerance Characterization - Reference 348
Jitter Tolerance Compliance 352
Jitter Tolerance Compliance - Concepts 352
Jitter Tolerance Compliance - Procedures 359
Jitter Tolerance Compliance - Reference 368
8 Solving Problems
Solving Problems - Concepts 375
Setup Problems 375
Setup Problems - Concepts 375
Measurement Problems 378
Measurement Problems - Concepts 378
Other Messages 384
Other Messages - Concepts 384
Problems with the N4916A 386
Problems with the N4916A - Concepts 386
9 Customizing the Instrument
Customizing the Instrument - Concepts 395
Restoring the System 395
Restoring the System - Procedures 395
Configuring the Instrument 397
Configuring the Instrument - Concepts 397
Configuring the Instrument - Procedures 398
Configuring the Instrument - Reference 400
Configuring the Touchscreen 400
Configuring the Touchscreen - Procedures 400
Configuring the Touchscreen - Reference 403
Installing Software Licenses 404
Installing Software Licenses - Procedures 404
Installing Software Licenses - Reference 405
Agilent J-BERT N4903 High-Performance Serial BERT 7

Installing Hardware Options 406
Installing Hardware Options - Procedures 406
Installing the N4916A 407
Installing the N4916A - Procedure 407
Installing Webserver 414
Customizing the Web Server- Concept 414
Printing 418
Printing - Procedures 418
File Management 421
File Management - Procedures 421
Preset Instrument State 425
Preset Instrument State - Procedures 425
Self Test 426
Self Test - Concepts 426
Self Test - Procedures 426
Self Test - Reference 427
Index 429
8 Agilent J-BERT N4903 High-Performance Serial BERT

1
Planning the Test
Planning the Test - Concepts
The following topics provide some information that can help you in
planning tests with the Serial BERT:
•“Introduction to the Serial BERT - Concepts ” on page 9 explains
the basics of bit error rates (BER) and BER testing with the Serial
BERT.
•“Which Test is Appropriate? - Concepts ” on page 13 provides you
with some basic information about the types of testing you can do
with the Serial BERT.
•“Connecting the DUT - Concepts ” on page 17 tells you how you
should connect your DUT to the Serial BERT.
Introduction to the Serial BERT
Introduction to the Serial BERT - Concepts
These topics explain some of the basics of BER, Serial BERT, and BER
testing with the Serial BERT.
Important Information about the Pattern Generator Outputs
The pattern generator output ports must be terminated with 50 Ωif they
are not connected:
•Data Out
•Data Out
Agilent J-BERT N4903 High-Performance Serial BERT
User Guide
sAgilent Technologies 9
S

•Clock Out
•Clock Out
Termination of output ports improves the test performance.
Important Information Regarding Security
The Serial BERT is a PC-based instrument with a standard Windows
operating system. As such, it is subject to the same security protection
measures as any other PC.
See the Microsoft web site for more information regarding data security:
http://www.microsoft.com/security/default.mspx
Every user must have administrator privileges to run the Serial BERT
firmware. Otherwise the firmware does not have access to the
instrument's hardware.
It ist recommended that you create a recovery disk for the instrument.
See “How to Restore the Operating System” on page 396.
Note also that there is a recovery image on the hard disk. See the
Windows Help for instructions on restoring a recovery image.
Understanding BER
Bit error ratio (BER) is the most fundamental measure of system
performance. It is the ratio of the number of errored bits to the total
number of bits received.
For example, 1 error in 1000 bits corresponds to a BER of 1/1000 or
1x10-3. This would be displayed on the instrument as 1E-3. Refer to the
following table to familiarize yourself with how BERs are displayed.
Notice that smaller exponents correspond to higher BERs, and larger
exponents correspond to lower BERs.
Table 1
Fraction Exponent Instrument Display
1/1 1 x 1001E+0
1/10 1 x 10-1 1E-1
1/100 1 x 10-2 1E-2
1/1000 1 x 10-3 1E-3
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10 Agilent J-BERT N4903 High-Performance Serial BERT

Table 1
Fraction Exponent Instrument Display
1/10,000 1 x 10-4 1E-4
1/100,000 1 x 10-5 1E-5
1/1,000,000 1 x 10-6 1E-6
1/10,000,000 1 x 10-7 1E-7
Understanding the Serial BERT
The Serial BERT, also referred to as a Bit Error Ratio Tester (BERT), is
a powerful instrument that enables you to analyze systems and
components in the telecommunication and enterprise communication
industries. It is an essential tool for designing and troubleshooting
communications systems, high-speed integrated circuits (ICs), and
photonic components. Its intuitive operation and leading edge
performance will help you quickly verify error performance.
The Serial BERT comes with advanced jitter generation capabilities for
jitter tolerance testing (J-BERT). The instrument provides:
•Excellent waveform performance
•Outstanding rise times and jitter performance
•A choice of logic family interfaces
•Easy object-oriented programming with the IVI-COM interface
•Remote commands similar to HP/Agilent 71603B
•A variety of ways in which to accumulate and view test results
•A collection of example patterns
•Convenient online documentation
•Automatic setup of optimum sampling point
•A variety of powerful advanced analysis tools
•Special support for jitter analysis and characterization
Which Features are Available?
The Serial BERT is available with different options. They differ in the
range of provided bit rates and in the available features.
Planning the Test 1
Agilent J-BERT N4903 High-Performance Serial BERT 11

Depending on the options you bought you can have the following
installed:
•C07
Bit rate range: 150 Mbit/s to 7 Gbit/s with built-in clock data recovery
(CDR)
•C13
Bit rate range: 150 Mbit/s to 12.5 Gbit/s with built-in CDR
•U13
Upgrade of a 7 Gbit/s instrument to 12.5 Gbit/s
•CTR, UTR
Option/Upgrade for adjustable CDR. The adjustable CDR has an
adjustable bandwidth, a selectable peaking, and an SSC tracking.
•A01
Bit Recovery Mode (measures BER without expecting a particular
pattern)
•J10, U10
Option/Upgrade for jitter injection. Total jitter can be composed
from random, periodic, sinusoidal, and bounded uncorrelated
sources.
•J11
Spread Spectrum Clock (SSC) generation.
•J12
Option/Upgrade for Jitter Tolerance Compliance tests. Use this test
to ensure that the jitter tolerance of the device under test complies
with a certain standard.
•J20
User-installable hardware module "Interference Channel" for
simulating intersymbol and sinusoidal interference
To check the options of your Serial BERT, press About in the Help menu.
The About dialog shows the installed options.
An external optional instrument is the N4916A De-Emphasis Signal
Converter. It is used to convert the output of the pattern generator to a
de-emphasized signal, as required by many standards such as PCI
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12 Agilent J-BERT N4903 High-Performance Serial BERT
N4916A De-Emphasis Signal Converter

Express, SATA 3 Gb/s, fully buffered DIMM, CEI, or 10 GbE.
Once the N4916A is connected, it can be conveniently controlled via the
Serial BERT.
Which Test is Appropriate?
Which Test is Appropriate? - Concepts
These topics help you to decide on the appropriate test setup for your
device.
Determining How to Test Your Device
The Serial BERT can help you test the performance of components and
systems for high-speed digital transmission equipment.
An important parameter of a digital system is the rate at which errors
occur in the system. The analyzer will compare the bits sent to your
device with the bits received from your device. It will record the number
of bit errors and display results such as the bit error ratio (BER). In
addition, accumulated results can be analyzed to help you determine
what caused the bit errors.
The analyzer can be set up to work with your device in many different
ways. To determine the best measurement setup, you must first decide
how you want to test your device. Before actually setting up and making
measurements, you may want to consider the following questions:
•What is the purpose of your test?
•What are the testing requirements of your device?
Planning the Test 1
Agilent J-BERT N4903 High-Performance Serial BERT 13

What is the Purpose of Your Test?
Does the purpose of your test fall under one of the following categories?
•To monitor instantaneous BER during measurement setup,
experiments, and adjustments. See “Instantaneous Measurements -
Concepts ” on page 297.
•To measure and log error performance over time. See “Accumulated
Measurements - Concepts ” on page 302.
•To measure the eye height and width of the incoming data signal at
specific alignment BER thresholds. See “Eye Measurements -
Concepts ” on page 310.
The following references may also be helpful in determining how to test
your device.
•For a list of recommended patterns for your device and application,
see “When to Use Which Pattern?” on page 26.
•For a list of recommended connection diagrams for your device and
application, see “Connecting the DUT - Concepts ” on page 17.
What are the Testing Requirements of Your Device?
Considering the requirements of your device will help you choose which
instrument functions to use during the test setup and when making
measurements.
•Do you need to use a custom test pattern?
If you have a long series of 1's or 0's in your custom pattern, be sure
to avoid false sync. See “What is False Synchronization?” on page
142
•Do you want to use alternating patterns?
Then you must first import or create a custom pattern that contains
an A half (pattern A) and B half (pattern B). See “Pattern Alternation
- Concepts ” on page 102.
•Are you aware of how custom pattern size can affect the pattern
output?
See “Why the Serial BERT Repeats Memory-Based Patterns” on page
31.
•Do you need more than two patterns or a mix of custom patterns and
PRBS?
•Does your device change the input pattern it receives?
If your device inverts logic, then select Data Inverted in the Sampling
Point Setup window. If your device changes patterns in other ways,
1Planning the Test
14 Agilent J-BERT N4903 High-Performance Serial BERT

then you must know the expected output pattern and select it as the
error detector reference pattern.
•What logic family is your device compatible with?
The pattern generator has preset voltage levels to work with ECL,
SCFL, LVPECL, LVDS, and CML. Be sure to select the correct logic
family. See “Understanding how the Serial BERT Uses Logic Families
and Terminations” on page 74.
•What is the input termination voltage of your device?
Make sure it is the same voltage as displayed in the pattern generator
termination list.
•What termination voltage is the output of your device designed to
work with?
Make sure it is set for the error detector's data port termination. See
“Data In Port Termination” on page 113.
•What bit rate do you need to test your device at?
The Serial BERT allows you to run tests from 150 Mb/s up to 12.5Gb/
s(depending on the options with which you bought the instrument).
See “Error Detector Bit Rate” on page 122 for more information.
•Does your device require differential inputs?
As complementary outputs, Data/Clock Out and Data/Clock Out may
satisfy this requirement. See “Diagram 2. Connections for
Differential Inputs” on page 18.
•Is the output of your device noisy or very small in amplitude?
You may need to manually set up a sampling point. See “Sampling
Point Setup - Concepts ” on page 126.
•Do you want to check the BER in bursts (for example, for loop testing
applications)?
The Serial BERT provides capabilities that help you set up and run
burst tests. See “Introduction to Burst Sync Mode” on page 144.
•Are you aware of how the sync mode setting can affect the way errors
are measured and displayed?
See “What Type of Synchronization Should You Use?” on page 141.
Test Times and Confidence Levels
A true BER measurement must be statistically valid. Because it is not
possible to predict with certainty when errors will occur, your device
must be tested long enough to have confidence in its BER performance.
The table below lists the test times required for different BERs at
specific bit rates.
Planning the Test 1
Agilent J-BERT N4903 High-Performance Serial BERT 15

N O T E The test times in this table are valid for continuous measurements. If measurements
are made in bursts, the test times will be longer (continuous test time divided by
the burst duty cycle times the burst sync ratio). See “Introduction to Burst Sync
Mode” on page 144 for background information.
The test times for 95% confidence level are:
Table 2
BER STM-64/
OC-192
(9.95328 Gb/
s)
STM-16c/
OC-48c
(2.48832 Gb/
s)
STM-4c/
OC-12c
(622.08 Mb/s)
STM-1/OC-3
(155.52 Mb/s)
1E-14 ~ 8.4 hours ~ 1.4 days ~ 5.6 days ~ 22.4 days
1E-13 ~ 50 minutes ~ 3.3 hours ~ 13 hours ~ 2.2 days
1E-12 ~ 5 minutes ~ 20 minutes ~ 80 minutes ~ 5.3 hours
1E-11 ~ 30 seconds ~ 2 minutes ~ 8 minutes ~ 32 minutes
1E-10 ~ 3 seconds ~ 12 seconds ~ 48 seconds ~ 3.2 minutes
The formula for confidence level is as follows:
C = 1 - e^-nb
Where:
C = degree of confidence (0.95 = 95%)
e = natural base number
n = number of bits examined without error
b = desired residual BER
You may want to prove that your device has a certain residual BER. If
you know this desired BER and the desired confidence level, you can
calculate the number of bits that must be measured without error. The
number of bits, in turn, can be translated into a period of time at a
certain bit rate. That is what is done in the above table.
The following example shows how to calculate the number of bits if the
desired BER (b) is 1E-10 and the desired confidence level (C) is 95%:
1Change formula "C = 1 - e^-nb" to solve for the number of bits (n)
n = -ln(1-C)/b
2Replace variables C and b
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16 Agilent J-BERT N4903 High-Performance Serial BERT

n = - ln(1 - 0.95)/1E-10
3Calculate the number of bits
n = - ln(1 - 0.95)/1E-10 = 2.99/1E-10 = 2.99E+10 bits
4Calculate the time period at the STM-16/OC-48 bit rate (2.48832 Gb/
s)
2.99E+10 / 2.48832E+9 = 12.016 seconds
Connecting the DUT
Connecting the DUT - Concepts
This section provides information on how to connect your DUT for
several common test scenarios.
N O T E The pattern generator's Data Out and Clock Out ports must be terminated with
50 Ω if they are not connected.
The following procedure is recommended when setting up a test:
1If your DUT can handle 0V, press the 0V (Disable) button in the PG
Output Setup screen.
The pattern generator's Data Out and Clock Out outputs are set to
0V. This is indicated in the PG Output Setup screen.
2Connect the DUT as necessary.
3Terminate any non-connected Data Out and Clock Out ports (normal
and complementary).
4If the outputs are disabled, press the 0V (Disable) button to enable
them.
To avoid damaging your device, set up the devices properly before
making connections.
Planning the Test 1
Agilent J-BERT N4903 High-Performance Serial BERT 17

CAUTION ESD can damage or destroy electronic components. Coaxial cables with both ends
unconnected may store electrostatic charges. Before connecting any coaxial cable
of this sort to a device or instrument, momentarily short the center and outer
conductors of the cable. When making connections, ensure the proper use of a
grounded, resistor-isolated wrist strap.
Connect your device according to the diagrams below:
Diagram 1. Connections for Different In/Out Data Rates
Often used for multiplexers, or when the data rate received by the device
is not equal to the data rate sent from the device.
Diagram 2. Connections for Differential Inputs
Application is the same as in Diagram 1. Illustrates how to connect to
a device requiring differential signals.
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18 Agilent J-BERT N4903 High-Performance Serial BERT

Diagram 3. Connections for an Amplifier
Often used for amplifiers.
Diagram 4. Connections for a Flip-Flop
Often used for flip-flops.
Planning the Test 1
Agilent J-BERT N4903 High-Performance Serial BERT 19

Diagram 5. Connections for a MUX/DEMUX Pair
Used to test multiplexer/demultiplexer (MUX/DEMUX) pairs. For
accurate measurement results, the timing of data signals between the
MUX/DEMUX pair must be set properly.
Diagram 6. Connections for a DCA or Oscilloscope (PGonly)
Used for measuring the output waveform of your device. For the least
amount of jitter, the clock output signal may be used as a trigger for the
oscilloscope.
1Planning the Test
20 Agilent J-BERT N4903 High-Performance Serial BERT