PURPOSE: To minimize a delay time of an output pulse and to prevent saturation of an internal circuit.

CONSTITUTION: After a charging/discharging waveform generating capacitor 11 is charged by a charging circuit 12, the charge is discharged by a discharge circuit 13 in a timing of an input discharge pulse. A charge/discharge waveform is generated synchronously with the input discharge pulse in this operation. The charging circuit 12 is provided with a means controlled by external control. A charge/discharge waveform and a specific voltage VA are given to a comparator 14, which compares them and provides an output of an output pulse. A charge/discharge waveform and a specific voltage VB are given to a comparator 15, which compares them and provides an output of an output pulse. A charge current of the charging circuit 12 is controlled by controlling the pulse outputted from the comparator 15. A rate of rise of a discharge start voltage is decreased with respect to the specific voltage VA under the control. As a result, the discharge time of the capacitor 11 is minimized.