| 摘要 |
PROBLEM TO BE SOLVED: To prevent the generation of a discontinuous part in an output signal outputted from an attenuation circuit or an amplifier circuit even at the time of suddedly changing the degree of attenuation or amplification by attenuating or amplifying amplitude based upon an amplitude zero point of an input signal. SOLUTION: An amplitude zero point for dividing an input signal into the amplitude of the positive polarity side and that of a negative polarity side is detected by a polarity edge detecting circuit 12. Since a volume control circuit 35 inputting a polarity edge detection signal from the circuit 12 outputs control data for an up/down counter 34 to an electronic volume 10 or 36 in synchronism with the edge detection signal, the volume 10 can attenuate the amplitude based upon the amplitude zero point of the input signal. Since the degree of attenuation of the volume 10 is adjusted in synchronism with the input signal, the degree of attenuation is not changed at a point close to the maximum amplitude of the input signal even when the degree of attenuation is suddenly changed, so that a discontinuous part is not generated in an output signal from the volume 10. |
