DIGITAL SIGNAL CONTROL VARIABLE GAIN AMPLIFIER

PROBLEM TO BE SOLVED: To reduce and suppress the generation of a transient noise resulted from the rapid change of a control signal, and to reduce and suppress, so called, feed-through. SOLUTION: A current control circuit 3 and a filter capacitor 4 are provided between the output terminal of a digital/analog converter 1 and a control signal input terminal 2a of a voltage controlled variable gain amplifier 2. The rapid rise or fall of the output signal of the digital/analog converter 1 is controlled by the current control circuit 3, and processed by, so called, a filter action by the filter capacitor 4 so that the rise and fall can be impressed to the control signal input terminal 2a as a slow signal. Thus, the generation of a transient noise resulted from the rapid rise and fall of a controls signal can be reduced, and feed-through can be suppressed.