Patent ID: 7015759
Filing Date: 2006-03-21
Classification: H03G

Abstract:
1. An AGC circuit comprising: a variable gain amplifier circuit having a gain controlled by a gain control signal; a rectifier circuit for rectifying an output signal of the variable gain amplifier circuit; a first voltage comparator for comparing a rectified signal rectified by the rectifier circuit with a voltage arbitrarily set beforehand; a first up/down counter for switching between an up count operation and a down count operation according to a level of an output voltage of the first voltage comparator; a first D/A converter circuit for outputting a voltage according to a count value of the first up/down counter; a second up/down counter for switching between an up count operation and a down count operation according to a level of an output voltage of a second voltage comparator; a second D/A converter circuit for outputting a voltage according to a count value of the second up/down counter; a second voltage comparator for comparing an output voltage of the first D/A converter circuit with an output voltage of the second D/A converter circuit; and a clock switch circuit for switching a count operation clock frequency of the first up/down counter based on the level of the output voltage of the second voltage comparator, wherein a gain control signal according to the output voltage of the first D/A converter circuit is supplied to the variable gain amplifier circuit.