Stratix V Device Handbook: Volume 2: Transceivers

ID 683779
Date 11/23/2021
Document Table of Contents Rate Match FIFO

The Rate Match FIFO (or clock compensation FIFO) compensates for minute frequency differences between the local clock (sometimes referred to as the FPGA soft IP clock or FPGA system clock) and the recovered clock. This is achieved by inserting and deleting SKP characters in the data stream to keep the FIFO from going empty or full, respectively.

The Rate Match FIFO is fully compliant with the GigE and PCI-Express (Gen1 and Gen2) protocols. For protocol configurations, the FIFO is automatically configured to support a clock rate compensation function as required by the following specifications:

  • The PCIe protocol per clock tolerance compensation requirement, as specified in the PCI Express Base Specification 2.0 for Gen1 and Gen2 signaling rates
  • The Gbps Ethernet (GbE) protocol per clock rate compensation requirement using an idle ordered set, as specified in Clause 36 of the IEEE 802.3 specification