| 摘要 |
PURPOSE:To vary the period with high accuracy and simple constitution by providing a means generating a one-shot pulse for oscillation start synchronously with an external clock signal, two shift registers, two selection means selecting the output and a timing distribution means. CONSTITUTION:The selection mode is a selector 3 is varied by the 1st control signal 302 to vary the phase of the output of a 1st shift register 2 and the output of a 2nd shift register 4 and then the start time of the next period at the same time. Moreover, a 1st timing distribution circuit 61, a 2nd timing distribution circuit 62 and a 3rd timing distribution circuit 63 have a delay element respectively. Then the pulse width among outputs 611-613, output 621, 623 and outputs 631-633 and the phase difference between the outputs are selected to an optional value. As a result, the oscillation period with high accuracy is obtained by using a signal having a period with high accuracy as an external clock.
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