| 摘要 |
PURPOSE:To obtain an output whose duty factor is 50% without malfunction even with DC level fluctuation of an input periodic wave, fluctuation of amplitude, distortion or mixture of noise by changing the reference level depending on the result of observing the duty of an output rectangular wave. CONSTITUTION:A comparator 1 compares the level of the input periodic wave with the reference level and outputs an output rectangular wave. The output rectangular wave is inputted to a count direction control input terminal of an up-down counter 5. The up-down counter 5 is reset to '0' by a latch signal synchronously with the output rectangular wave to count the clock. The output of the up-down counter 5 is ORed with a gate signal by an AND gate 4, the result is fed to an adder 3 and added to the output of a latch register 2, that is, the reference level. The result of addition is latched by a latch signal and stored in the latch register 2 as a reference value.
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