PURPOSE: To contrive to decrease the circuit current by replacing a resistor into an equivalent resistance block formed by circuits of parallel connection each having two switches whose drive clocks are inverted to each other between the terminal and a ground terminal of a capacitor.

CONSTITUTION: A three-stage of low pass filter, for example, consists of an operational amplifier 10 employing resistors RA, RB, an input capacitor C1, a feedback capacitor C2, an input stage capacitor C3, and the 1st ∼ 3rd two- terminal circuit block 11 ∼ 13. The 1st ∼ 3rd two-terminal circuit blocks 11 ∼ 13 are operated by switching 2 parallel capacitors CR1 ∼ CR3 switched alternately by switches S1, S2. The 1st ∼ 3rd blocks 11 ∼ 13 are regarded as a prescribed value of resistance. Thus, the filter characteristic is decided by the capacitance ratio Li/CRi of the capacitors and the clock frequency fs. Moreover, a 2nd order LPF is obtained by eliminating the 3rd block 13 and the capacitor C3 from the configuration stated above.