PURPOSE: To reduce the sum of capacity element values and to reduce the occupied area of an integrated circuit by using an inversional amplifier having the amplification factor of once as an operational amplifier.

CONSTITUTION: A switch SW1 for switching one end of a capacitor element Co to an input terminal IN and the earth and a switch SW2 for switching the other end of the element Co to the inversional input of an inversional operational amplifier Ampl and the earth are arranged. The noninversional input of the Ampl is earthed and a capacitor element Cf is connected between the inversional input and an output. The amplifier having the amplification of '1' is used in the constitution. As compared to an ordinary switched capacitor circuit (the amplification factor of the Ampl is 10000 times), the sum of the capacitor element values can be reduced and the area occupied by a chip can be reduced when the titled circuit is constituted of an integrated circuit.