PURPOSE: To obtain a filter circuit that can miniaturize a semiconductor chip by making charging and discharging to a capacitor by an MOSFET of P and N channel.

CONSTITUTION: The MOSFETQ11 becomes on when a clock signal 1 supplied as a gate signal is positive polarity and charges charge corresponding to voltage level of an input signal V1 to a capacitor C11. On the other hand, when the clock signal 1 supplied as a gate signal is negative polarity, the FETQ11 becomes off and checks charging to the capacitor C11. FETQ12 becomes on, and charge charged in the capacitor C11 is charged to a capacitor C12 through the FETQ12. Thus, a filter circuit consisting of a resistance R' and a capacitor C' is obtained. As an output signal V2 is obtained by using only one clock line l1, the semiconductor chip can be miniaturized.