PURPOSE: To prevent an adverse influence due to a parasitic capacity by having a switched capacitor provided with a switch consisting of a capacitor in which a form and the capacity are unified and a MOS transistor in which the form is unified as a circuit element and providing the circuit element as an unit at the required position of the capacitor.

CONSTITUTION: The circuit element 16a is connected between the input terminal of an arithmetic amplifier 2 and the input terminal of an input signal Vi and the circuit element 16b is connected between the negative input terminal of the arithmetic amplifier 2 and an output terminal. The circuit elements 16a and 16b are constituted of the MOS transistor in which the analog switched 18a, 18b have the same form. The analog switches 20a and 20b are constituted of the MOS transistor of the same form. When the capacity of the capacitors Ca, Cb is defined to be C, the parasitic capacity to be ΔC, the capacities of the circuit elements 16a, 16b are respectively (C+ΔC).