| 摘要 |
PURPOSE:To eliminate the need for offset adjustment by supplying an absolute value output to a sinusoidal wave input to one input terminal of a comparator and supplying a setting level to the other input terminal so as to output a square wave of a prescribed duty. CONSTITUTION:In impressing a sinusoidal wave AC input to an input terminal 11, an absolute value output is obtained at an output terminal 35 of an absolute value amplifier 12 and the absolute value output is supplied to a positive input terminal of a voltage comparator 15. On the other hand, a constant voltage being a VD/2 obtained at an output terminal 36 of a double integration circuit 33 is fed to a positive input terminal of a differential amplifier 29. A setting level voltage being a Vsin(pi/4) obtained at an output 37 of the differential amplifier 29 is fed to a negative input of the voltage comparator 15. Thus, since the voltage comparator 15 sends an output when the inputted absolute output reaches a value of Vsin(pi/4) or over, an output voltage of square wave whose duty is 50% is obtained as the output of the voltage comparator 15.
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