PURPOSE: To obtain an output signal which is subjected to correct waveform shaping by performing sampling/holding over two stages and also specifying the phase difference and the wave height of a sampling pulse.

CONSTITUTION: The input signal given from a terminal 5 is supplied to a source follower circuit 21 via a source follower circuit 11. The output of the circuit 21 is supplied to an inverter amplifier 23 via a sampling/holding circuit 22. The output of the amplifier 23 is supplied to an inverter amplifier 26 via a sampling/ holding circuit 24. Then an output signal which is subjected to waveform shaping is obtained from an output terminal 15. The sampling pulses SH1 and SH2 supplied to the circuits 22 and 24 have different phases by 180° from each other. At the same time, the crest value of the SH2 is set smaller than that of the SH1. In such a way, the variance of the output DC level which is due to the sampling process can be reduced effectively. Thus it is possible to obtain an output signal that is subjected to correct waveform shaping.