| 摘要 |
There is provided a semiconductor device having a voltage-controlled oscillator outputting an output clock signal; N pieces of control units generating a frequency-divided clock signal by frequency-dividing the output clock signal, comparing a reference clock signal and the frequency-divided clock signal, and outputting an output signal based on a comparison result; an adder adding output signals from each of the control units; and a low-pass filter filtering an output of the adder and outputting to the voltage-controlled oscillator, wherein setting information related to a frequency division ratio made of N pieces of data cycled and supplied in a sequence in synchronization with the frequency-divided clock signal is supplied to each of the control units with initial values made different from one another and a frequency-division operation and a comparison operation are performed thereby to form a moving average filter by N pieces of control units and to reduce a quantization noise, so that occurrence of a spurious in the output clock signal can be suppressed.
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