Apparatus and method for feedback mitigation in a low speed communications receiver

摘要

A method and apparatus is shown for controlling the input gain of a receiver wherein the input gain is controlled by sampling an amplified data signal during a time interval when a positive-going feedback transient from an output terminal of the receiver to an input terminal of the receiver is not present in the amplified data signal. An embodiment of a receiver circuit according to the present invention includes an input amplifier having variable gain determined by a gain control signal, a comparator which compares the amplified data signal from the input amplifier to a detection threshold voltage to produce a demodulated data signal and an analog delay circuit which delays the amplified data signal by a predetermined time interval to produce a delayed data signal. A switch is driven by the demodulated data signal to sample the delayed data signal for input to an automatic gain control circuit. The automatic gain control circuit compares the sampled delayed data signal to an automatic gain control threshold potential and rectifies and integrates the resulting waveform to produce the gain control signal. An embodiment of the method of the present invention amplifies a data signal by a gain factor compares the amplified data signal to a detection threshold voltage to produce a demodulated data signal, and delays the amplified data signal to produce a delayed data signal. The method then samples the delayed data signal using the demodulated data signal to produce a sampled data signal that is used to adjust the gain factor.