| 摘要 |
A problem of the invention is to provide a wide band modulation PLL having an excellent modulation accuracy at low cost. With respect to a PLL portion including VCO ( 21 ), a divider ( 22 ), a phase comparator ( 23 ), and a loop filter ( 24 ), a dividing ratio of the divider ( 24 ) is modulated by a dividing ratio generating portion ( 29 ) by controlling a control voltage of VCO ( 21 ) by a control signal generating portion ( 30 ). VCO ( 21 ) includes two control terminals, and the control signal generating portion ( 30 ) inputs the control signal to one of the control terminals. In controlling a modulation degree, the dividing ratio generating portion ( 29 ) is inputted with a calibration data f<SUB>c1 </SUB>and the control signal generating portion ( 30 ) is inputted with a calibration data f<SUB>c2</SUB>. A demodulator ( 31 ) demodulates output signals of VCO ( 21 ) when the respective calibration data are inputted and modulation degree controlling means ( 32 ) outputs a modulation degree control signal to the control signal generating portion ( 30 ) based on the demodulated signals.
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