Stratix V Device Handbook: Volume 2: Transceivers

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

The receiver FIFO block operates in different modes based on the transceiver datapath configuration.

The Custom and Low Latency PHY IPs automatically select an appropriate receiver FIFO mode for the configuration you use; however, you should select the receiver FIFO mode when using the Native PHY IP.

Clock Compensation Mode

The receiver FIFO is configured in clock compensation mode for the 10GBASE-R configuration. In clock compensation mode, the FIFO deletes idles or ordered sets and inserts only idles to compensate up to a ±100 ppm clock difference between the remote transmitter and the local receiver.

Generic Mode

The receiver FIFO is configured in generic mode for the Interlaken configuration. In generic mode, the receiver FIFO provides the FIFO partially empty and FIFO full status signals to the FPGA fabric to control the read side of the FIFO.

Phase Compensation Mode

The receiver FIFO is configured in phase compensation mode for the 10G custom configuration. In phase compensation mode, the FIFO compensates for the phase difference between the FIFO write clock and the read clock.

Note: Altera recommends a minimum of 32 words for the soft FIFO depth in the FPGA fabric for the following conditions:
  • When the 10G PCS RX FIFO is set to register mode
  • When using the recovered clock to drive the core logics
  • When there is no soft FIFO being generated along with the IP Catalog