PURPOSE: To obtain satisfactory characteristics in both pass frequency bands adjacent to an eliminated band without the influence upon the characteristic upon a BEF by setting a voltage, which is applied to the inductance of LC ladder filter parallel branches, and a current, which is flowed to the resistance of series branches, to the output of an operational amplifier.

CONSTITUTION: For the purpose of maximizing the dynamic range of a filter in consideration of both of distortion characteristic and noise characteristic, node voltages are so scaled that maximum output voltages of respective operational amplifiers of the filter are equal to one another. Though the output of an operational amplifier 406 becomes 1/R when the value of a feedback capacitor 411 of the operational amplifier 406 is increased R times, the charge transfer quantity to the next stage is reduced by the reduction of the output. Consequently, values of the capacitor and a switched capacitor which are connected directly to the output terminal of the operational amplifier 406 are increased R times for the purpose of preventing the change of charge transfer quantity before and after scaling. In an SCF having the BEF characteristic which is realized in this manner, a stable filter characteristic which is not affected by the variance of IC producing processes is obtained by the advantage that the element sensitivity of the LC ladder filter is zero.