F-Tile Architecture and PMA and FEC Direct PHY IP User Guide

ID 683872
Date 9/29/2025
Public
Document Table of Contents

A.6.1.2.2. FGT Receiver Adaptation

The FGT PMA supports automatic receiver adaptation for data rates greater than 7Gbps, and scrambled data, to meet the most advanced NRZ and PAM4 protocols over the range of all supported data rates and across temperature variations.

The FGT PMA also supports manual settings for tuning. For lower than 7Gbps applications, or 9.8Gbps unscrambled mode CPRI or GPON applications, which usually use unscrambled data, you can disable auto adaptation to use the manual tuning mode. This is because, for these unscrambled data applications, DFE may have a challenge to converge and thus introduce errors or may result in performance degradation if auto adaptation is ON. To disable auto adaptation, you can choose the manual tuning mode in the F-Tile PMA/FEC Direct PHY IP or add the QSF assignments in the .qsf file from FGT PMA Settings: Manual Tunning .

You can confirm whether auto adaptation is disabled by:
  1. Searching in the support_logic/top_auto_tiles.sv file or support_logic/top_auto_tiles.bcm.txt file for FLUX_MODE_BYPASS.
  2. Reading out register at address 0x47854, and if the return value is 0xB1, auto adaptation is enabled. If the return value is not 0xB1 auto adaptation is disabled. This address is for channel 0. For all other channel addresses, refer to Accessing FGT PMA Registers.

To dynamically switch between auto adaptation enable and disable, you can use the F-Tile Dynamic Reconfiguration Suite IP.