Cyclone V Device Handbook: Volume 2: Transceivers

ID 683586
Date 10/24/2018
Public
Document Table of Contents

2.2.3. Receiver Clocking

This section describes receiver clocking, which is the clocking architecture internal to the receiver channel of a transceiver.
Figure 46. Clocking Architecture for Receiver PCS and PMA Configuration


The CDR in the PMA of each channel recovers the serial clock from the incoming data and generates the parallel clock (recovered) by dividing the serial clock (recovered). The deserializer uses both clocks. The receiver PCS can use the following clocks depending on the configuration of the receiver channel:

  • Parallel clock (recovered) from the CDR in the PMA
  • Parallel clock from the clock divider that is used by the channel’s transmitter PCS
Table 38.  Clock Sources for All Receiver PCS Blocks
Block Side Clock Source
Word aligner - Parallel clock (recovered)
Rate match FIFO Write Parallel clock (recovered)
Read Parallel clock from the clock divider
8B/10B decoder -
  • Rate match FIFO is not used-Parallel clock (recovered)
  • Rate match FIFO is used-Parallel clock from the clock divider
Byte deserializer Write
  • Rate match FIFO is not used-Parallel clock (recovered)
  • Rate match FIFO is used-Parallel clock from the clock divider
Read Divided down version of the write side clock depending on the deserialization factor of 1 or 2, also called the parallel clock (divided)
Byte ordering - Parallel clock (divided)
Receiver (RX) phase compensation FIFO Write Parallel clock (divided). This clock is also forwarded to the FPGA fabric.
Read Clock sourced from the FPGA fabric