Patent ID: 7397872

Claim:
An automatic gain control circuit for control of an amplification gain of a reception signal comprised of a data signal to the header part of which is added a burst portion including at least a preamble signal, comprising: an automatic gain control amplifier for amplifying the reception signal by a gain in accordance with a gain control signal; a reception signal power monitor for receiving and detecting a power of the reception signal; a delay unit for delaying an output derived from the automatic gain control amplifier by a predetermined time; a burst detector for performing correlation between the output derived from the automatic gain control amplifier and the output signal of the delay unit to detect the burst portion of the reception signal and output a first burst synchronization detection signal; and an amplification gain controller for outputting the gain control signal to the automatic gain control amplifier, said gain control signal having first, second and third gains, in sequence, said first gain being set in advance in response to a trigger signal indicating the start of burst detection, said second gain being calculated as a function of the power of the reception signal detected by the reception signal power monitor, and said third gain being calculated as a function of the power of the reception signal produced at the output of the automatic gain control amplifier at the time the gain control signal has said second gain and in response to the first burst synchronization detection signal from the burst detector.