Keysight Technologies D9020DDRC, Manual

Page: 267 / 370

DDR2(+LP) Compliance Testing Methods of Implementation 251
Data Strobe Timing (DST) Tests 15
Measurement Algorithm
1 Acquire and split read and write burst of the acquired signal.
2 Take the first valid WRITE burst found.
3 Find all valid rising DQS middle crossings in this burst.
4 Find the first DQS rising edge by searching for the earliest rising crossing point in all of the found
DQS middle crossing points. Take the found point (first DQS rising edge) as the tDQSS strobe
point.
5 Find the closest Clock-DQS (the Clock middle crossing point that is closest to the first DQS rising
edge).
6 Find the tDQSS Clock point which is the rising clock middle crossing point one cycle before the
closest Clock-DQS.
7 Compare the tDQSS strobe point to the tDQSS clock point as the test result.
Mathematically, the test result = tDQSS strobe point - tDQSS clock point.
8 Display the test result by going to the measurement location on the waveform and locate the
marker to tDQSS strobe point and tDQSS clock point.
9 Compare the test result against the compliance test limit.