| 摘要 |
PURPOSE: To decrease the number of external addition circuits and to reduce noise by descrambling a video intermediate frequency(VIF) signal or a signal obtained by detecting the VIF signal in a circuit at a post-stage of an intermediate frequency amplifier circuit. CONSTITUTION: A descrambler 10 is made up of a video amplifier circuit 51 provided in the inside of a VIF amplifier detection IC 15, a descrambling processing circuit 11 inserted between a video detection circuit 52, changeover switch circuits 12, 13, a through-connection wire 14, a scramble detection circuit 31 and a scramble control circuit 32. Since the VIF amplifier detection IC 15 receives an external control signal for descrambling to descramble a scrambled signal, the signal is descrambled in a stage of a VIF whose band is limited and amplified after a SAW filter 4 or a video signal with a lower frequency at a signal level higher than an output level of a tuner section 1. As a result, a switching noise is reduced. |
