| 摘要 |
PURPOSE:To detect the frequency fluctuation without giving any effect on the characteristic of an oscillator independently of the characteristic of the oscillator by detecting the deviation of the frequency of an input signal as a high/low frequency based on the normal frequency. CONSTITUTION:The width of the input signal 101 depends on the frequency. The input signal 101 is delayed or a prescribed time by a delay line 1 to form clock signals 102, 103 of shift registers 2, 3. Thus, when the pulse width of the input signal 101 is longer (low frequency) than the delay time decided by the delay line 1, the shift registers 2, 3 reading the clock signal at its leading reads a signal '1' and an output '1' is sent. Further, the output of the register 2 is inverted by an inverter 4 to detect conversely it that the pulse width is short. The consecutive detection for a prescribed number of times or over is detected by AND gates 5, 6, then a high/low frequency detection signal is outputted.
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