Teledyne LeCroy QPHY-BroadR-Reach - Manual (Page 22)

Test 2 - Transmitter Jitter (Master) and Transmit Clock Frequency
This test measures the MDI output jitter, J
TXOUT
, as specified in Section 5.4.3 and the transmit clock
frequency as specified in Section 5.4.5. This test requires that the DUT be placed in test mode 2.
What is Measured:
The oscilloscope captures a 1 ms acquisition at 10 GS/s relative to an unjittered reference resulting in
10 Mpts. By sampling in this manner, very low frequency components are filtered out. The RMS of J
TXOUT
is then calculated and compared to 50 ps. Using the same acquired signal the symbol rate is also
measured. Additionally, the rise and fall times are calculated for informational purposes.
Test Methodology:
The oscilloscope is set to acquire 10 Mpts at 10 GS/s. The acquired signal has two bits of enhanced
resolution (ERES) applied to it in order to limit the bandwidth of the oscilloscope to a value which is
suitable for this measurement. The RMS value of the jitter track for the acquired signal is calculated. The
calculated value is then compared to 50 ps using pass/fail testing. The bit rate (half of the symbol rate) of
the acquired signal is also measured and the compared to 33.3 MHz +/- 100 ppm using pass/fail testing.
Lastly, the 10%-90% rise and fall times are calculated for information purposes.
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