JPH05335904

PURPOSE:To make the time from the reception of a trigger signal till signal output constant by using a SIN wave oscillator and a COS wave oscillator in common and using a voltage of an oscillating source as a comparison object at a point of trigger time so as to comparate a voltage of an oscillating source. CONSTITUTION:A SIN waveform oscillation circuit 1 and a COS waveform oscillation circuit 2 respectively output a SIN waveform and a COS waveform being reference signals, a phase discriminator 3 detects the phase of the SIN waveform oscillation circuit 1 and the COS waveform oscillation circuit 2 when a trigger signal is received and outputs a threshold level and control signals A, B used for comparators 4, 5. The comparators 4, 5 respectively compare the SIN waveform and the COS waveform with the threshold level and a switch 6 selects an output of the comparators 4, 5 based on a control signal B and an exclusive OR circuit 7 takes exclusive OR between the output of the switch 6 and the control signal A. Furthermore, a delay circuit 8 delays an external trigger signal and an AND circuit 9 outputs AND between outputs of the circuit 7 and a delay circuit 8.