Stratix V Device Handbook: Volume 2: Transceivers

ID 683779
Date 11/23/2021
Document Table of Contents Scrambler

In a multi-lane link environment, each of the transmitter lanes may implement a LFSR for scrambling. The LFSR uses the following polynomial: G(X) = X23 + X21 + X16 + X8 + X5 +X2 + 1. It is a standard PRBS23 polynomial. The scrambler is used to provide enough edge density, since there is no 8B/10B encoding in PCIe Gen3, so that the RX PMA CDR can lock to the incoming data stream and generate the recovered clock.