Keysight Technologies N5991ST3A SATA, Руководство пользователя

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64 Keysight N5991 SATA Test Automation Software Platform User Guide
5 Receiver Tests
Rcvr Jitter Tolerance Test
This test is available for all data rates.
Purpose and Method
The Rcvr Jitter Tolerance Test determines how much jitter a DUT can
tolerate at different SJ frequencies.
The test procedure depends on the selected value of the Search Algorithm
property. The different types of Search Algorithms are explained below.
The selected algorithm is sequentially used over a range of jitter
frequencies. At each jitter frequency value the maximum jitter amplitude
where the DUT produced no more frame errors than the Number of
Allowed Frame Errors is stored as the max passed jitter value. The result is
a curve that shows the maximum jitter that the DUT can tolerate over the
SJ frequency. It reflects the Rx clock data recovery (CDR) characteristics of
the DUT. Typically the CDR can follow low frequency jitter (f < Rx
phase-locked loop (PLL) bandwidth) better than high frequency jitter (f >
Rx PLL bandwidth).
Search Algorithms
• Binary
The binary search algorithm is used. The jitter amplitude is initially set
to the middle of the tested range. When the DUT passes the BER test,
the jitter amplitude is increased, and when the DUT fails the test, the
amplitude is reduced. At each step, the step size is reduced until the
target resolution is reached.
• Linear
The test uses the defined step size to go linearly from “Start Jitter”
upwards until the DUT fails the BER test.
• Linear with two step sizes
The test first uses relatively large steps to go linearly from “Start Jitter”
upwards. When the DUT fails the BER test, the test goes back to the
last passed point and steps up again with small steps until an error is
found again.
• Linear with two step sizes and hysteresis
The test first uses relatively large steps to increase the jitter amplitude
linearly from “Start Jitter”. When the DUT fails the BER test, the jitter
amplitude is taken back down in mid-sized steps until the DUT passes
again. From there the amplitude is stepped up again in small steps until
an error is found again.