PURPOSE: To filter PWM signals by using a switched capacitor filter, which does not require any high sampling frequency, and to easily make a circuit into an IC by supplying signals to a switched capacitor after integrating them with a PWM integrator.

CONSTITUTION: The digital data of the prescribed sampling frequency are inputted from an input terminal 4 to an interpolator 2, and interpolation is executed by increasing the frequency. The signal passes through a D/A converter 3 and corresponding to a control signal generated at a switched controller 5, a fixed current is integrated with a PWM integrator 5. The output is inputted to a switched capacitor to execute band control, further passes through a low-pass filter 7 to remove the higher hamonic component and is outputted from an analog signal output terminal 8.