Patent ID: 7561863

Claim:
An automatic gain control device, comprising: a first gain adjustment part for amplifying the gain of a received signal; a second gain adjustment part for reducing the gain of said received signal; a level detection part to detect levels of said received signal in each of a plurality of frequency bands; an A/D converter to convert level detected signals in each band detected by said level detection part to digital signals; and a digital signal processor to determine the enabled/disabled state of the gain adjustment by said first gain adjustment part and said second gain adjustment part and a gain adjustment amount based on level detected digital signals of each band outputted from said A/D converter, wherein said digital signal processor adjusts the gain of said second gain adjustment part so that a value of the level detected digital signal outputted from said A/D converter becomes equivalent to a prescribed value when the value of the level detected digital signal is larger than said prescribed value, but not exceeding a gain adjustable limit level in said second gain adjustment part, and adjusts the gain of said first gain adjustment part while maintaining a gain adjustment amount of said second adjustment part around said limit level when the value of the level detected digital signal exceeds said limit level.