Gain varying device capable of varying each gain of analog and digital signals

摘要

A gain varying device includes a zero-cross detector for detecting a zero cross or a vicinity thereof in an input analog or digital signal, an analog gain varier for varying the gain of the input analog signal, and a digital gain varier for varying the gain of the input digital signal. In this device, the timing to vary the gain of the analog or digital signal in the individual gain varier is determined in accordance with the zero-cross detection timing, so that smooth switching can be realized in the gain varying operation without generation of any audible noise.