PURPOSE: To output a signal, in which a repeated component is not included, by providing an active RC low-pass filter which is provided in the front stage of a switched capacitor low-pass filter and interrupts components more than 1/2 in a sampling frequency caused by the switched capacitor low-pass filter among components of higher harmonic frequency.

CONSTITUTION: For a signal inputted from a signal input terminal 1, an amplitude is limited by an amplitude limiter 2 not so as to be larger than a certain level and the signal is inputted to an overlap block filter 4 of a splutter filter 3. At such a time, the spectrum of the signal is shown by a code 7 in a figure. For the signal distorted by the amplitude limiter 2, the higher harmonic component is attenuated in this filter 4 and a band is limited to the condition of O≤f<fs<2. A signal 8, whose band is limited by the overlap block filter 4, is outputted from an output terminal 6 without overlapping a repeated component 9 by a switched capacitor low-pass filter 5.