Adaptation of Feed-Forward Equalizer Settings: A Frequency Domain Analysis Approach

Abstract

Characteristics of the channel has a major e ect on the signal integrity. The channel distortion is increased with high-rate data transmission. Feed-Forward Equalizer (FFE) at transmitter side is one of the methods that can be used to compensate the e ect of the channel. PCIe-Gen3, 4, and 5 standards specify some constraints on the FFE settings and assign some preset values that can be used based on the e ect of FFE on time-domain. In this paper, detailed analysis for the FFE in frequency domain is presented. New preset values are recommended to achieve enhancement on the behavior over di erent channels. Short and long channel models are created based on the PCIe standard specifications to check the suggested preset values with worst channels. Continuous-Time Linear Equalizer (CTLE) also is modeled to check the e ect of FFE with di erent CTLE boost values. The eye-measurements based on the new preset values is enhanced by 10% with respect to the default preset values in PCIe specifications for short and long channel. Mapping the preset value in the frequency domain helps fine tuning process for FFE settings by facilitating more guidance to get the best FFE settings.