PURPOSE: To make capacitance large by providing a buffer circuit, a first resistor whose one terminal is connected to the input of the circuit, a capacitor in which one terminal is connected to the input of the buffer circuit and another terminal is grounded and a second resistor connected to another terminal of the first resistor and the output of the buffer circuit.

CONSTITUTION: This device is provided with resistors 21 and 22, a complex impedance element 23 and a buffer circuit 24. The resistance value of the resistor 21 is defined as R01, the resistance value of the resistor 22 is defined as R00, the impedance of the complex impedance element 23 is defined as Z, the current of the resistor 21 is defined as I1, the current of the resistor 22 is defined as I0, and an input current at this time is defined as (i). When a voltage V2 at one terminal of the complex impedance element 23 is grounded, equivalent capacity is increased. Therefore, the equivalent capacitance is turned to be 20 times on the conditions of R01=5kΩ and R00=95kΩ. At this time, the capacitor required for capacitance constitution of 1000pF can be 50pF. Thus, a high cut filter can be realized even in the low frequency band without any external addition.