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Keysight Technologies
Jitter Measurements on Long
Patterns Using 86100DU-401
Advanced Waveform Analysis
Application Note
Introduction
Today's devices are characterized using a variety of test patterns. A commonly used test sequence for jitter
and eye analysis is the Psuedo-Random Binary Sequence (PRBS) having 2^31-1 bits in length. Why test using
PRBS-31? PRBS patterns are easy and inexpensive for devices to generate using hardware, and a long pat-
tern like PRBS-31 (2^31-1 bits, or 2,147,483,647 bits) includes bit sequences that effectively stress baseline
wander and clock wander in devices.
Total Jitter (TJ) on a PRBS-31 signal can be measured directly using a Bit Error Ratio Tester (BERT), but in
order to achieve reasonable confidence in the result, test times can be long. PRBS-31 patterns are too long
for jitter analysis tools that analyze every edge in a pattern and then estimate TJ based on random jitter (RJ)
and deterministic jitter (DJ) measurements.
As an alternative to using long patterns, some Implementation Agreements such as the Optical Internetwork-
ing Forum - Common Electrical Interface (CEI) 2.0 developed short stress patterns (SSP) that ensure similar
stress levels as PRBS31, but have pattern lengths that are short enough for today's jitter analysis tools.1
However, since these SSP are memory based patterns (software), many of today's devices do not have the
ability to generate such SSP.
The 86100D DCA-X Wide-Bandwidth Oscilloscope with Option 200 Enhanced Jitter Analysis is well known
for its speed and accuracy. Its speed comes from the fact that, while in Jitter Mode, the DCA targets over
99% of its samples in the crossing region where jitter information resides (it does not waste time taking many
samples where there is no jitter information). Accurate jitter analysis algorithms were developed using trace-
able amounts of jitter generated by a precision jitter transmitter,2 and are documented in Application Note
86100C-1.3 However, like most jitter analysis tools, detailed jitter analysis on every edge of the pattern is
limited to patterns that are 2^16 bits in length or less.
To overcome pattern length limitations found in many of today's jitter analysis tools, Keysight Technologies,
Inc. developed a Microsoft Office Excel-based application called 86100DU Option 401 Advanced Waveform
Analysis. Option 401 controls an 86100D DCA-X mainframe and provides: