| 摘要 |
PROBLEM TO BE SOLVED: To provide a front-end circuit that can receive analog television broadcast programs and a digital television broadcast programs in common. SOLUTION: The front-end circuit is provided with a band-pass filter 17S, that separates an audio intermediate frequency signal SIFS from an intermediate frequency signal SIF and an analog/digital converter circuit 21S that converts the signal SIFS into a digital signal DIFS, and also a DSP 22S that applies audio detection to the signal DIFS and generates an AGC signal DAGCS from the signal DIFS, a variable gain amplifier 18S that applies AGC to the signal SIFS are provided, a band-pass filter 17P that separates a video intermediate frequency signal SIFP from the signal SIF and extracts it, an analog/digital converter circuit 21P that converts the signal SIFP into a digital signal DIFP are provided, and a DSP 22 that applies video detection with respect to the signal DIFP is provided. The AGC signal DAGC is generated from the signals SIFS, SIFP, and AGC is applied to the signal SIF as a result of this signal DAGC. |
