| 摘要 |
PROBLEM TO BE SOLVED: To provide a frequency synthesizer for improving the fluctuation of a sprious reduction effect caused by an output frequency concerning the frequency synthesizer of a fractional frequency dividing system. SOLUTION: This frequency synthesizer is provided with a fixed frequency divider for frequency-dividing the output of a crystal oscillator and outputting it to a phase comparator as a reference frequency, charge pump for charging/discharging a loop filter with a current corresponding to a phase difference outputted from the phase comparator, voltage controlled oscillator (VCO) for inputting the output of the loop filter, variable frequency divider for supplying a signal variably frequency-dividing the output of the VCO to the other input terminal of the phase comparator, frequency dividing number generating means for applying an integer frequency dividing number to the variable frequency divider and controlling it, phase error compensating means for generating a current for compensating a phase error having time width generated on the basis of a phase error compensation value outputted from the frequency dividing number generating means and the output of the VCO while connecting the output to the output of the charge pump, and clock generating means for supplying a clock to the frequency dividing number generating means by inputting the output of the VCO.
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