AUTOMATIC GAIN CONTROL CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide an AGC circuit from which a more stable output signal can be obtained even when ambient temperature and a power supply voltage are fluctuated. SOLUTION: The AGC circuit is provided with an analog variable gain amplifier circuit 10 that includes fixed gain amplifiers 181-18n and a selector 20 that selects their output signals, an A/D converter 12, a digital band pass filter 14 that passes only a burst signal and a chrominance signal, and an AGC/ detection circuit 16 that controls a gain of the amplifier circuit 10 so as to make the burst signal constant, amplifies a digital signal BPFout so that the detected burst signal is equal to a digital reference signal to obtain a digital output chrominance signal Cout.