| 摘要 |
PURPOSE:To extract the frequency information of an inputted analog signal by a simple circuit constitution by comparing said analog signal with an analog signal shifted by a prescribed position from said analog signal at their levels. CONSTITUTION:An analog signal VIN is amplified and converted at its polarity by amplifiers 5a, 5b. The output VIN1 of the amplifier 5a is supplied to a comparator 7 as it is, but the output VIN2 of the amplifier 5b is phase-delayed only by a time constant determined by a resistor 12 and a capacitor 13 and the delayed signal is reached the comparator 7. The comparator 7 compares the level of the signal VIN1 with that of the signal VIN2 phase-delayed from the signal VIN1 and outputs a square wave alternate signal VIN3 to be alternated at twice the frequency of the signal VIN1. The signal VIN3 is rectified by a full-wave rectifying circuit 14 and outputted as a sqaure wave pulse signal VIN4 and the signal VIN4 is divided at its frequency by a 1/2 counter 15 and outputted as a square wave pulse signal VIN5 having the same frequency as the analog signal VIN.
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