| 摘要 |
PURPOSE:To obtain a rectangular wave whose duty ratio is 50% without using a frequency being twice of a required frequency by controlling a time when a sawtooth waveform crosses an output voltage waveform based on the output of a comparator comparing the output of a sawtooth wave generating means the output voltage of a reference voltage generating means to obtain a rectangular wave. CONSTITUTION:The titled circuit comprises a sawtooth wave generating circuit 5 connected to an input terminal 4, a comparator 7 comparing the output of the sawtooth wave generating circuit 5 and the output of the reference voltage generating circuit 6, and control circuit 8 applying a control voltage to the sawtooth wave generating circuit 5 based on the output of the comparator 7. An operational amplifier 17 or the like of the control circuit 8 obtains a difference between the rectangular wave being the output of the comparator 7 and the mean voltage of its inversion, and uses the result as a control voltage so as to apply negative feedback, and in this embodi ment, an output terminal of the operational amplifier 17 is connected to a connecting point between a capacitor 13, and a resistor 14 of the sawtooth wave generating circuit 5. Thus, the frequency used for the circuit is the same in frequency as the rectangular wave obtained at an output terminal 9.
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