PURPOSE: To prevent phase delay from being increased in a sample servo system and a hazard from occurring in a continuous servo system when this circuit is used as the filter of the servo circuit of an optical disk.

CONSTITUTION: When an input waveform shows a continuous wave, a clock () and an inversion clock INV are supplied from a clock generation circuit G1 to a first switched capacitor filter F1 and a second switched capacitor filter F2 so that they can be operated with negative phases mutually, and when the input waveform shows a sample waveform, the clock () and the inversion clock INV are supplied from the clock generation circuit G1 to the first switched capacitor filter F1 and the second switched capacitor filter F2 so that they can be operated with in-phases mutually.