Teledyne LeCroy QPHY-DDR4 - Manual (Page 55)

QPHY-DDR4 Software Option
tQSH/tQSL, DQS Output High/Low Time
These tests measure the high time (tQSH) and low time (tQSL) for each valid DQS transition during a R
burst. Both the maximum and minimum tQSH/tQSL values are measured.
These tests are very similar to
tQSH and tQSL, which are measured on R bursts.
Note: Only tQSH will be discussed below. The measurement methodology is the same for the tQSL
expect the measurement is made on DQS from falling edge to a rising edge instead of a rising edge
to a falling edge.
After the completion of the tQSH test the oscilloscope is in the following configuration:
Figure 43 - Oscilloscope Configuration after the tQSH 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” tQSH measurement indicated by t@tQSHmin. A
trace label is applied at Vref on this trace according to the signal name assigned to DQS.
Figure 44 – tQSH/tQSL Results
In the Measure section:
• tQSH (P1) is measuring the high time of DQS. The high time is determined by measuring the time
DQS crosses Vref on a rising edge at to the time DQS crosses the next associated falling edge at
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