Determining Window Size in ps - 1.0 English

Versal Adaptive SoC Soft DDR4 SDRAM Memory Controller LogiCORE IP Product Guide (PG353)
Document ID
PG353
Release Date
2023-10-18
Version
1.0 English

To determine the window size in ps, first calculate the tap resolution and then multiply the resolution by the number of taps found in the read and/or write window. The tap resolution varies across process (down to variance at each nibble within a part).

However, within a specific process, each tap within the delay chain is the same precise resolution.

  1. To compute the 90° offset in taps, take (BISC_PQTR – BISC_ALIGN_PQTR).
  2. To estimate tap resolution, take (1/4 of the memory clock period) / (BISC_PQTR – BISC_ALIGN_PQTR).
  3. The same then applies for NQTR.

BISC is run on a per nibble basis for both PQTR and NQTR. The write tap results are given on a per byte basis. To use the BISC results to determine the write window, take the average of the BISC PQTR and NQTR results for each nibble. For example, ((BISC_NQTR_NIBBLE0 + BISC_NQTR_NIBBLE1 + BISC_PQTR_NIBBLE0 + BISC_PQTR_NIBBLE1) / 4).