Patent ID: 7076223

Claim:
A gain control device comprising: a variable gain amplifier for amplifying an input signal with a gain corresponding to a control voltage applied thereto; a power detector for outputting an output voltage corresponding to an input power or an output power of said variable gain amplifier; a control circuit for outputting the control voltage based on an output voltage of said power detector for controlling the output power of said variable gain amplifier with respect to a target value; a packet detection circuit for detecting a packet signal by means of the output voltage from said power detector and outputting a packet detection signal; a timing circuit for outputting a timing signal after an elapse of a predetermined time after a start of outputting the packet detection signal from said packet detection circuit; a sample-hold circuit for sampling-and-holding the control voltage from said control circuit in response to the timing signal from said timing circuit; and a switch circuit for providing the control voltage from said control circuit for said variable gain amplifier until the timing signal is output from said timing circuit, and providing the control voltage held by said sample-hold circuit for said variable gain amplifier in response to outputting of the timing signal.