Patent ID: 8059834

Claim:
An automatic gain control circuit comprising: an electronic volume that amplifies an input audio signal in a variable gain and outputs the amplified input audio signal; a reference level generator that outputs a reference level; a level judging unit that compares a level of the input audio signal with the reference level outputted by the reference level generator and outputs a comparison result signal for indicating whether or not the level of the input audio signal is higher than the reference level; and a controller which increases or decreases predicted level data indicative of a level range to which the level of the input audio signal is predicted to belong, among a plurality of level ranges of the input audio signal, based on the comparison result signal, controls the reference level generator to output a value of the reference level corresponding to the level range indicated by the predicted level data, and controls a gain of the electronic volume in response to the predicted level data, wherein the gain of the electronic volume is controlled so that a level of a signal output from the electronic volume, which is determined based on a level of the input audio signal and the gain of the electronic volume, does not exceed an amplitude upper limit level.