| 摘要 |
PURPOSE:To make it possible to detect the peak point of an input sine wave even if the frequency of said sine wave is changed, by controlling an incremental/decremental counter operated by two clocks different in frequency by the input sine wave. CONSTITUTION:A comparator 1 discriminates the voltage of a sine wave (a) to obtain an one-bit logical signal and the output thereof receives frequency dividing by a D flip-flop 9 so as to obtain 1/2-frequency. At gates 7, 8, two kinds of clocks alternately different in frequency are outputted on every other cycle every when the cycle of an input sine wave is changed and inputted to an incremental/ decremental counter 5 as incremental/decremental signals. When a figure-down signal is outputted from the counter 5, the differentiation of wave front is performed by a wave form shaping circuit 3 and a signal coincided with the peak point of the input sine wave is outputted in a ratio of one time per two cycles. Further, this peak point detection signal is also used as the reset signal of the counter 5 or a latch 10.
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