| 摘要 |
In a semiconductor device capable of radio communication, a stable clock signal is generated even if a reference clock signal for generating a clock signal has varied frequencies in each cycle. A clock signal generation circuit includes an edge detection circuit that detects an edge of an input signal and generates a synchronization signal, a reference clock signal generation circuit that generates a clock signal which functions as reference, a counter circuit that counts the number of edges of rise of the reference clock signal in accordance with the synchronization signal, a duty ratio selection circuit that selects a duty ratio of a clock signal from a count value, and a frequency division circuit that generates the clock signal having the selected duty ratio.
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