| 摘要 |
PURPOSE:To correct the duty ratio to 1:1 by using a current mirror circuit and a capacitor so as to convert a square wave to which duty ratio is deviated from 1:1 and phase differs by 180 deg. from each other into a charge/discharge waveform. CONSTITUTION:The titled circuit is provided with a constant current circuit 8, 1st and 2nd current mirror circuits 9, 11 operated by the output of the circuit 8, operation control means 11, 12 switching the current mirror circuits 9, 11 into the operation/stop state, 1st and 2nd capacitors C1, C2 charged/discharged by the output current of the constant current circuit 8 is response to the operation/stop and a comparator 13 comparing the output voltages of the capacitors C1, C2 to output a square wave signal. Thus, the two square waves to which duty ratio is deviated and phase differs by 180 deg. from each other are converted into a charge/discharge waveform by the capacitors C1, C2 and the current mirror circuits 9, 11 to eliminate the effect of one gate propagation delay time, and since the inversion by the voltage comparison is always of the same period, a square wave to which duty ratio is 1:1 is obtained.
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