Teledyne LeCroy QPHY-DDR4 - Manual (Page 54)

Figure 41 - Oscilloscope Configuration after the tDQSQ_total test
Shown on this screen:
• 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” tDQSQ measurement indicated by t@tDQSQmax. A
trace label is applied at Vref on this trace according to the signal name assigned to DQS.
• Z3 is a zoom of F3, the acquired DQ signal after any probe deskew has been applied. The zoom is
position at the location of the “worst case” tDQSQ measurement indicated by t@tDQSQmax. A
trace label is applied at Vref on this trace according to the signal name assigned to DQ.
Figure 42 – tDQSQ_total Results
In the Measure section:
• tDQSQ (P1) is measuring the skew between DQS at Vref and DQ at Vref for each DQ transition.
Essentially the time between the two trace labels is measured. The maximum value is the
measured value for tDQSQ_total Max reported in mUI. 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 R bursts were in the acquired waveform.
• t@tDQSQmax (P3) displays the location of where the maximum value of tDQSQ occurred. This is
used to position the zoom traces at the location of the “worst case results”.
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