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

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

A.6.3.4. F-Tile FGT Receiver Setting Recommendations

When auto adaptation is ON , links with all data rates across different reaches work with proper Transmitter equalizer settings.

As a rule of thumb, you should disable auto adaptation if your data rate is less than 7 Gbps. For data rates higher than 7 Gbps, if the data is unscrambled, you may disable auto adaptation. For example, for CPRI 9.8G unscrambled data, you should use the manual tuning mode. If the data rates are above 7 Gbps and the data is scrambled, you should use auto adaptation. For GPON applications, you should use the manual tuning mode.

The following table shows the recommended starting point of receiver equalization settings if you want to disable auto adaptation with your data unscrambled. You need to sweep the three parameters to find best BER. If data is scrambled, you should set auto adaptation to ON. For manual tuning applications, tuning the TX equalization is the first order and tuning the RX equalization is the second order in link optimization.
Table 128.  Receiver Equalization Starting Point Tuning Recommendations
Data Rates (Gbps) Signaling Mode Adaptation Mode Starting Point Setting
<= 7 Gbps,

unscrambled data

NRZ Manual tuning

VGA Gain = 0

High frequency boost = 61

DFE tap 1 = 24

9.8 Gbps CPRI,

unscrambled data NRZ

NRZ Manual tuning

VGA Gain = 17

High frequency boost = 34

DFE tap 1 = 0

7-32 Gbps,

scrambled data

NRZ Auto adaptation No RX equalization tuning needed
20-58.125 Gbps,

scrambled data

PAM4 Auto adaptation No RX equalization tuning needed