PURPOSE: To decrease number of components and to miniaturize the chip area by using a switched capacitor circuit having a positive/negative equivalent resistor in a notch filter circuit.

CONSTITUTION: An input signal E1 connects to a capacitor 41 and a switched capacitor SC circuit 42 having a positive equivalent resistor respectively. The other end of the capacitor 41 connects to a non-inverting input of an operational amplifier circuit 43. An SC circuit 44 having a negative equivalent resistance is connected between an output terminal and the non-inverting input of the amplifier circuit 43 and a capacitor 45 is connected between the output terminal and an inverting input respectively. The other end of the SC circuit 42 connects to the inverting input of the amplifier circuit 43 and an SC circuit 46 having a positive equivalent resistance is connected between the inverting input of the amplifier circuit 43 and a common potential. Through the forming above, number of components is saved and the chip area is miniaturized in circuit integration.