PURPOSE: To adjust the selectivity of a switched capacitor filter by dividing a switched capacitor equivalent resistor into two groups and making its clock frequency different.

CONSTITUTION: The switched capacitor filter is provided with four switched capacitor equivalent resistors 1∼4. The equivalent resistors 1 and 2, and 3 and 4 are used respectively as a pair and divided into two groups. Then a clock CK 2 and its inverted signal are given to the equivalent resistors 1, 2 from a selection circuit 13 and a clock CK 1 and its inverted signal are given to the equivalent resistors 3, 4 from the selection circuit 13. The selectivity Q of the switched capacitor filter depends on the ratio of the two clock frequencies. Thus, the selectivity Q is adjusted depending on the ratio of the clock frequency.