Teledyne LeCroy QPHY-DDR4 - Manual (Page 63)

QPHY-DDR4 Software Option
• Z2 is a zoom of F2, the acquired DQS signal after any probe deskew has been applied. The zoom is
positioned at the location of the “worst case” tDQSS measurement indicated by t@tDQSSmax. A
trace label is applied at Vref on this trace according to the signal name assigned to DQS.
Figure 54 – tDQSS Results
In the Measure section:
• tDQSS (P1) is measuring the skew between CK and DQS. The skew is measured between
CK rising
at Vref to the nearest DQS rising at Vref . Essentially the time between the two trace labels is
measured. The maximum value is the measured value for tDQSS max and is reported in
mtCK(avg). This test is considered informational only since the limit is undefined.
• tDQDQS (P2) is measuring the skew between DQ and DQS. Since this measurement is performed
once per burst, this shows how many W bursts were in the acquired waveform.
• t@tDQSSmax (P3) displays the location of where the maximum value of tDQSS occurred. This is
used to position the zoom traces at the location of the “worst case results”.
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