Teledyne LeCroy QPHY-USB3-Tx-Rx - Manual (Page 29)

QPHY-USB3-Tx-Rx Software Option
917719 Rev A
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At the completion of the CP 0 Jitter Test the oscilloscope is in the following configuration:
Figure 15 - Oscilloscope Configuration after CP0 Ji tter Test
On this screen there are 2 traces visible. They are the TI E Hi stogram and the Bathtub Curve. Again, the Tj, Rj
(spectral) and Dj (spectral) are display ed in the S DA Jitter section. However, as per the USB 3.0 SuperSpeed
Electrical Compliance Test Specification, the Rj that was measured on CP 1 is injected into this measurement.
Additionally the minimum pulse widt h in the acquired waveform is measured in P1. A verage UI is not shown on
the screen, but is report ed with the other results.
Figure 16 - Test Report from Jitter Te sts
Test 1.3.2 Phase Jitter Slew Rate
The purpose of this test group is to verify that the jitter slew rate is within the specification limits . This is a
measure of how fast the PLL in a USB 3.0 receiver has to change in order to keep up with chan ges in the clock
frequency. Performing this test requires calculation of the first derivative of the PLL Track. The PLL Track is a
waveform that shows the phase change that the PLL was able to follow and track out of the signal. By taking the
first derivative of the PLL Track we can easily measure the minimum and maximum phase jitter slew rate on the
derivative waveform.