| 摘要 |
A frequency adjustment circuit that maintains a target frequency even when frequency adjustment data of zapping circuit is changed by an external noise is offered. The frequency adjustment circuit includes a reset signal generation circuit, a frequency adjustment data latch circuit that latches and retains the frequency adjustment data ZP 1 and ZP 2 generated by a first zapping circuit and a second zapping circuit based on a latch clock ZCLK and a latch clock generation circuit that generates the latch clock ZCLK. The reset signal generation circuit generates a periodic reset signal ZRES that is synchronized with a rise of an enable signal EN generated from an interface circuit. The latch clock generation circuit generates the latch clock ZCLK that is synchronized with a fall of the enable signal EN.
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