Teledyne LeCroy QPHY-DDR4 - Manual (Page 56)

Vref. The minimum value is the measured value for tQSH min 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@tQSHmin (P4) displays the location of where the minimum value of tQSH occurred. This is used
to position the zoom traces at the location of the “worst case results”.
tQH_total, DQ Output Hold Time
The purpose of this test is to characterize the earliest invalid transition of DQ. This measures the
minimum time from
DQS at Vref to the next DQ transition at Vref.
After the completion of the tQH_total test the oscilloscope is in the following configuration:
Figure 45 - Oscilloscope Configuration after the tQH_toal 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” tQH measurement indicated by t@tQHmin. 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” tQH measurement indicated by t@tQHmin. A trace
label is applied at Vref on this trace according to the signal name assigned to DQ.
Figure 46 – tQH_total Results
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