PURPOSE: To correct the cycle of positive sine waves and negative sine waves to output triangular waves and a phase difference by a method wherein an analog switch is controlled at the cycle of the ON/OFF operation of a binary counter and sine waves which are formed by the binary counter during the ON/OFF operation are separated into positive since waves and negative sine waves at two cycles.

CONSTITUTION: The clock of a 4024 binary ripple counter 1 is used as data, a 4028 decoder 3 is used as a multiplexer switch, an output is inverted so as to be used, the output is input to an operational amplifier 6 as a D/A converter, and the output is converted into since waves so as to be fetched. In addition, the phase difference between triangular waves and the sine waves is fetched by an operation amplifier 7, and approximate sine-wave pulses are output. After that, a positive output and a negative output are separated by a 4053 analog switch 4 on another time base of the 4024 binary ripple counter 1. Thereby, the cycle of positive sine waves and negative sine waves which output the triangular waves and the phase difference can be made precise.