Arria® V Device Handbook: Volume 2: Transceivers

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

2.2.2. Transmitter Clocking

Transmitter (TX) clocking refers to the clocking architecture that is internal to the TX channel of a transceiver.

The following figure shows how the clock divider provides the serial clock to the serializer, and the parallel clock to the serializer and TX PCS. When the byte serializer is not used, the parallel clock is used to clock all the blocks up to the read side of the TX phase compensation FIFO. For configurations with the byte serializer, the parallel clock is divided by a factor of two for the byte serializer and the read side of the TX phase compensation FIFO. The read side clock of the TX phase compensation FIFO is also forwarded to the FPGA fabric to interface the FPGA fabric with the transceiver.

Figure 52.  Clocking Architecture for Transmitter PCS and PMA Configuration


Table 43.  Clock Sources for All TX PCS Blocks
PCS Block Side Clock Source
TX Phase Compensation FIFO Write FPGA fabric write clock, driven either by tx_clkout or tx_coreclkin
Read Parallel clock (divided). Clock forwarded to FPGA fabric as tx_clkout
Byte Serializer Write Parallel clock (divided) either by factor of 1 (not enabled), or factor of 2 (enabled)
Read Parallel clock
8B/10B Encoder Parallel clock
TX Bit Slip Parallel clock

The following figure shows how the clock divider provides the serial and parallel clock to the serializer in a transmitter PMA configuration. The parallel clock is forwarded to the FPGA fabric to interface the FPGA fabric with the TX PMA directly, bypassing the PCS blocks.

Figure 53.  Clocking Architecture for Transmitter PMA Only Configuration


Transmitter 10G PCS Clocking for GZ Devices

The following figure shows the clocking scheme for the transmitter 10G PCS and transmitter physical medium attachment (PMA). The clock divider block provides the serial clock to the serializer of the transmitter PMA and the parallel clock to the transmitter PCS. In the 10G PCS channel, the parallel clock is used by all the blocks up to the read side of the transmitter (TX) FIFO.

Figure 54. Transmitter 10G PCS Clocking for GZ Devices