| 摘要 |
PROBLEM TO BE SOLVED: To perform the voltage transformation of a PWM signal up to the voltage level required on the side of a tuner without damaging characteristics in simple configuration. SOLUTION: The power supply terminal of a digital amplifier circuit 81 composed of a CMOS gate circuit or the like is connected between a power supply terminal 85, to which a power supply voltage is supplied, and the ground. The input terminal of the digital amplifier circuit 81 and an AGC output terminal 45 of a demodulation circuit 42 are connected. By supplying the output of this digital amplifier circuit 81 through smoothing circuits 82 and 84 and a resistor 83 to an AGC input terminal 32 of a tuner 31, the circuit can be simplified without damaging the characteristics of the tuner 31.
|
