Our custom board could pass sanity test at 792MHz frequency. However, several parameters do not have good margins when running the full shmoo, especially AutocaloffsetDQDQs and DqsIvref. These two results do not have obvious trends on how to adjust the parameters for the next step.
For AutocaloffsetDQDQs, it failed both on the left and right, only two items in the middle passed. For DqsIvref, the margin in the middle is not good, shmoo results did not become better after tuning x axis and y axis.
Below are my questions.
What does DqsIvref mean and which factors on board will influence DqsIvref performance? The +1.35V power current ripple is about 50mv on our board when running full shmoo, would that be the reason of poor DqsIvref result?
In terms of AutocaloffsetDQDQs, does anyone have any suggestions for us to try?