Patent ID: 7542529

Claim:
A wireless receiving device processing a received signal made of a signal frame having a known signal section at a leading part, comprising: an amplification portion amplifying said received signal in an analog form with a variable gain; an analog/digital conversion portion converting said amplified received signal in the analog form to a digital signal; a filter portion band-limiting said digital signal; a demodulation processing portion having an output of said filter portion coupled thereto, and performing demodulation processing according to a predetermined demodulation scheme on said band-limited digital signal; a gain control portion providing a control output controlling said variable gain to said amplification portion in accordance with a level of the received signal amplified in said amplification portion; a switch portion selectively outputting any one of an output of said analog/digital conversion portion and the output of said filter portion to said gain control portion; a control signal generating portion generating a control signal designating a timing of the selective output operation in said switch portion; and a count portion counting a symbol number from a count starting point in accordance with a reference clock, the count starting point being a starting point of the signal frame of each received signal outputted by said demodulation processing portion, wherein said control signal generating portion generates a first control signal at the starting point of each signal frame, and when the symbol number counted by said count portion reaches a predetermined value, generates a second control signal, said switch portion outputs the output of said analog/digital conversion portion to said gain control portion in response to said first control signal, and outputs the output of said filter portion to said gain control portion in response to said second control signal, and said predetermined value corresponds to a signal section length required by said gain control portion for processing of the variable gain at the leading part of said received signal.