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Question regarding technote MG543184 compensated flight time measurements in DDRx wizard

Question asked by bpsplett on Apr 11, 2011
Latest reply on Apr 13, 2011 by weston_beal

My question is what is used as a test load?  a 50ohm resistor on the DQ output to gnd?  Is the test load the same across all different double data rate interfaces ----> DDR-DDR2-DDR3, also I am a little confused about the context below....the text implies testloads for both DQ and DQS.  the example shows DQ for setup time, what would the DQS test load be used for?

 

 

 

Product: HyperLynx SI/PI

 

The Setup Time (From Sim) measurement on the rising edge DQ with respect to rising edge of DQS is shown in the diagram below.

You can assume that DDRx Wizard uses compensated flight time for Setup (From Sim) and Hold Time (From Sim) as long as the DQ and DQS driver models are the same with the same testload according to the following equation:

Setup Time (From Sim) = DQS Compensated Flight Time - DQ Compensated Flight Time.

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