Automatic gain control system having hysteresis switching

Abstract

The invention provides an automatic gain control system having hysteresis switching. The system comprises an error calculator, a hysteresis comparator, a first automatic gain control loop and a second automatic gain control loop, wherein the error calculator is used for calculating a first estimation signal and a preset take over point (TOP) so as to generate an error signal; the hysteresis comparator is used for comparing the first estimation signal with the preset TOP so as to generate a control signal; the first automatic gain control loop is used for generating a first gain control signal according to the control signal so as to control the gain of a first variable gain amplifier; the second automatic gain control loop is used for generating a second gain control signal according to the control signal so as to control the gain of a second variable gain amplifier; and when the first estimation signal leaves the hysteresis region of the hysteresis comparator, the first gain control signal and the second gain control signal are increased or decreased progressively, so that the total gain value varies stably.

Description

technical field [0001] The invention relates to an automatic gain control system, in particular to a double-loop automatic gain control system based on hysteresis switching and with a stable change in total gain value. Background technique [0002] figure 1 It is a block diagram of an existing automatic gain control (Automatic Gain Control, AGC). An antenna 102 receives wireless communication signals. A coordinator 100 includes a bandpass filter 104 to select a wide frequency spectrum containing signals. A low noise amplifier 106 amplifies the broadband signal selected by the bandpass filter 104 according to a fixed amplification factor. A variable gain amplifier 108 according to a control signal V RF to amplify the output signal of the low noise amplifier 106. A downconverter 110 reduces the output signal of the variable gain amplifier 108 from RF to IF. The band-pass filter 112 performs narrow-band filtering to generate a narrow-band signal. A variable gain amplifie...

AI Technical Summary

Problems solved by technology

[0008] The purpose of the present invention is mainly to provide an automatic gain control system with hysteresis switching, which uses a hysteresis comparator to solve the problems of system instability and noise increase caused by frequent switching

At the same time, it also solves the problem of error caused by the sudden increase or decrease of the gain generated by using the hysteresis comparator

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