Automatic gain compression detection and gain control for analog front-end with nonlinear distortion

摘要

An analog front-end (AFE) circuit has at least one AFE stage to generate a conditioned analog signal, and a gain control block to set a gain of the AFE stages. A finite state machine (FSM) block sets the gain to a baseline set gain without gain compression, or a current set gain with gain compression. An amplitude block determines amplitudes of the inner and outer eyes of a signal eye of the conditioned analog signal at the baseline set gain and the current set gain. A compression calculation block determines a gain compression of the conditioned analog signal at the current signal gain based on the relative changes in the respective amplitudes of the inner and outer signal eyes between the baseline and current set gains. The FSM block increases the current set gain until the gain compression ratio reaches a predefined limit.

主权项

1. A method of controlling a gain of an analog front-end (AFE) circuit, the method comprising:
setting the gain to a baseline set gain; determining an inner eye baseline amplitude of an inner eye of an eye pattern of a signal at the baseline set gain, and an outer eye baseline amplitude of an outer eye of the eye pattern of the signal at the baseline set gain; setting the gain to a current set gain higher than the baseline set gain; determining a gain compression ratio based on the inner eye baseline amplitude, the outer eye baseline amplitude, an inner eye current amplitude of the inner eye of the eye pattern at the current set gain, and an outer eye current amplitude of the outer eye of the eye pattern at the current set gain; and increasing the current set gain until the gain compression ratio reaches a predefined limit.