Patent ID: 7595692

Claim:
An automatic gain control circuit for generating a gain control signal for controlling the gain of a variable gain amplifier block in accordance with an output of the variable gain amplifier block, the automatic gain control circuit comprising: a count control signal generating block for generating a count control signal according to the output of the variable gain amplifier block; an up-down counter for upcounting an upcount clock signal or downcounting a downcount clock signal according to the count control signal; a gain control signal generating block for generating the gain control signal corresponding to a count value of the up-down counter; and a downcount clock signal generating block for generating the downcount clock signal whose frequency corresponds to the count value of the up-down counter, wherein: the gain control signal generating block includes a digital-to-analog converter for converting the count value of the up-down counter to a voltage, and the downcount clock signal generating block is a voltage controlled oscillator whose oscillation frequency is controlled by an output of the digital-to-analog converter.