Automatic gain controller and automatic gain control method, and radio communications apparatus equipped with automatic gain control function

摘要

An automatic gain controller has variable gain amplifiers (11a), (11b) for variably amplifying the input signals (RI1), (RI2) and a control loop that respectively performs automatic gain control of these variable gain amplifiers (11a), (11b) via feedback control of the output signal level. Variation amount in the detected output of the demodulated outputs (RD1), (RD2) is detected in the variation amount detector (20) . The control section (19) selects the control loop where the output signal level is the highest when the variation amount is small and the system is in the stable state, and performs automatic gain control via a gain control signal in this control loop and correction gain control signals in the other control loops, and places in the non-operating state the gain control signal generator of the other control loops.