L- and H-Tile Transceiver PHY User Guide

ID 683621
Date 1/30/2024
Public
Document Table of Contents

5.3.2.3. Rate Match FIFO

The rate match FIFO compensates for the frequency differences between the local clock and the recovered clock up to ± 300 ppm by inserting and deleting skip/idle characters in the data stream. The rate match FIFO has several different protocol specific modes of operation. All of the protocol specific modes depend upon the following parameters:

  • Rate match deletion—occurs when the distance between the write and read pointers exceeds a certain value due to write clock having a higher frequency than the read clock.
  • Rate match insertion—occurs when the distance between the write and the read pointers becomes less than a certain value due to the read clock having a higher frequency than the write clock.
  • Rate match full—occurs when the write pointer wraps around and catches up to the slower-advancing read pointer.
  • Rate match empty—occurs when the read pointer catches up to the slower-advancing write pointer.

Rate match FIFO operates in the following modes:

  • Basic 10-bit PMA
  • Basic 20-bit PMA
  • GbE
  • PIPE
  • PIPE 0 ppm