Arria® 10 Transceiver PHY User Guide

ID 683617
Date 4/01/2024
Public
Document Table of Contents

5.1.8. Loopback

The PMA supports serial, diagnostic, and reverse loopback paths.

Figure 235. Serial Loopback PathThe serial loopback path sets the CDR to recover the data from the serializer while data from receiver serial input pin is ignored by the CDR. The transmitter buffer sends data normally. Adjusting the TX VOD, TX pre-emphasis, and RX CTLE settings does not have an effect on the serial data that goes through the serial loopback path. Adjusting the RX VGA and RX DFE settings has an effect on the serial data that goes through the serial loopback path.
Figure 236. Reverse Serial Loopback Path/Pre CDRThe reverse serial loopback path sets the transmitter buffer to transmit data fed directly from the VGA output. Adjusting the RX CTLE, and RX VGA settings has an effect on the serial data that goes through the diagnostic loopback path.
Figure 237. Reverse Serial Loopback Path/Post CDRThe reverse serial loopback path sets the transmitter buffer to transmit data fed directly from the CDR recovered data. Adjusting the RX CTLE, RX VGA, and RX DFE settings has an effect on the serial data that goes through the reverse loopback path. Adjusting TX VOD and TX pre-emphasis has an effect on the transmitter serial differential output data.