Arria® V Device Handbook: Volume 2: Transceivers

ID 683573
Date 5/29/2020
Public
Document Table of Contents

2.2.3. Receiver Clocking

Receiver clocking refers to the clocking architecture internal to the receiver channel of a transceiver.
Figure 63. 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 46.  Clock Sources for All Receiver PCS Blocks
PCS Block Side Clock Source
Standard 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
10G28 All other PCS blocks
  • Regular mode: parallel clock (recovered)
  • Loopback mode: parallel clock from the clock divider.29
Figure 64. Clocking Architecture for Receiver PMA Only Configuration The parallel recovered clock from the CDR and deserializer is forwarded to the FPGA fabric to interface FPGA fabric with the receiver PMA directly, bypassing the PCS blocks.


Clocking Architecture for Receiver 10G PCS and the Receiver PMA for GZ Devices.

Figure 65. Clocking Architecture for 10G PCS and the Receiver PMA for GZ Devices


28 Available for Arria V GZ devices only.
29 For more information about loopback mode, refer to the Transceiver Loopback Support chapter in Arria V Devices.