L- and H-Tile Transceiver PHY User Guide

ID 683621
Date 1/30/2024
Document Table of Contents RX PMA Use Model

The Adaptive Parametric Tuning (ADAPT) engine allows the continuous time linear equalization (CTLE) and decision feedback equalization (DFE) blocks of the RX PMA to adapt to an optimal value.

Adaptation is available for CTLE, VGA, and DFE. The RX PMA Adaptation Modes include:

  • Manual CTLE, Manual VGA, DFE Off
  • Adaptive CTLE, Adaptive VGA, DFE Off
  • Adaptive CTLE, Adaptive VGA, All-Tap Adaptive DFE
  • Adaptive CTLE, Adaptive VGA, 1-Tap Adaptive DFE
  • ctle_dfe_mode_2 (Adaptive Mode for PCIe Gen3) — This mode fixes the AC gain and leaves everything else adaptive.
Table 84.  RX PMA Adaptation Range of Values
Analog PMA Setting Range of Values

AC gain: 0-15

EQ gain: 0-47

VGA 0-31
DFE (Adaptive only)

Tap1: -63 to 63

Taps 2-3: -31 to 31

Taps 4-7: -15 to 15

Taps 8-15: -7 to 7