DIGITAL FREQUENCY DETECTOR AND DIGITAL PLL USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a digital frequency detector to be used for a digital PLL or a frequency synthesizer, and a digital PLL using the digital frequency detector.

SOLUTION: A digital frequency detector includes: a first conversion unit which uses a first ring oscillator that operates in a high-level period of a first frequency to output the first frequency as first frequency information of a digital type; a second conversion unit which uses a second ring oscillator that operates in a high-level period of a second frequency to output the second frequency as second frequency information of a digital type; and an operation unit which operates a ratio of the first frequency information and the second frequency information to output a digital frequency for the first frequency.

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