Visible to Intel only — GUID: hco1416492571765
Ixiasoft
Visible to Intel only — GUID: hco1416492571765
Ixiasoft
1.17.4.3. Centering DQ/DQS
The following figure illustrates a four DQ/DQS group per-bit-deskew and centering.
To align and center DQ and DQS, the sequencer finds the right edge of DQ signals with respect to DQS by sweeping DQ signals within a DQ group to the right until a failure occurs. In the above figure, DQ0 and DQ3 fail after six taps to the right; DQ1 and DQ2 fail after 5 taps to the right. To align the DQ signals, DQ0 and DQ3 are shifted to the right by 1 tap.
To find the center of DVW, the DQS signal is shifted to the right until a failure occurs. In the above figure, a failure occurs after 3 taps, meaning that there are 5 taps to the right edge and 3 taps to the left edge. To center-align DQ and DQS, the sequencer shifts the aligned DQ signal by 1 more tap to the right.