Automatic gain control apparatus

摘要

In an automatic gain control amplifier (AGCa), an RF automatic gain controller (2) controls the gain of a radio frequency signal (Srf). A frequency converter (3, 4) frequency-converts the radio frequency signal (Srfa) into an intermediate frequency signal (Sifa). An IF automatic gain controller (5) controls the gain of the intermediate frequency (Sifa). A level detector (LDa) detects a signal level of the gain-controlled intermediate frequency signal (Sifa), and generates a level signal (SLa). An automatic gain control signal generator (SGa, SGb) separately controls, based the level signal (SLa, SLb), the RF automatic gain controller (2) and the IF automatic gain controller (5).