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

ID 683872
Date 12/15/2021

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Document Table of Contents FHT Gray-Coder and Pre-Coder

PAM4 patterns generated in PAM4 mode are gray-encoded by default. For NRZ signals, the gray-coder is bypassed.

Table 14.  Gray-Coder
Linear Gray
00 00
01 01
10 11
11 10

The transmitter also includes an optional pre-coder that you can enable for both PAM4 and NRZ signals. Once you turn it on, it performs 1÷(1+D) encoding on all data bits until you disable it.

For the FHT gray-decoder and pre-decoder, reverse the process for the FHT gray-coder and pre-coder.