PURPOSE: To simplify the circuit and to attain the low power consumption by utilizing an operation amplifier circuit provided in common to other output operation while one of two switched capacitors connected in cascade fetches an input signal.

CONSTITUTION: When a timing signal (a) is at a high level, an operational amplifier circuit OP acts like an operation amplifier circuit OPa in an equivalent circuit and an output signal of an active low-pass filter is fetched in a capacitor C1 as the input signal. When a timing signal (b) is at a high level, the operational amplifier circuit OP acts like an operational amplifier circuit OPb and fetches the input signal into a capacitor C2. The circuit acts like the oscillation circuit by the repetitive operation by the timing signals (a, b). Thus, the oscillation circuit consists of one operational amplifier circuit OP, a simple switch circuit and capacitors C1, C2.