发明授权

PLL circuit
摘要:
A PLL circuit of one embodiment has a structure for preferably setting the FV characteristic of an LC-VCO. The PLL circuit includes a voltage controlled oscillator, a phase comparator, a charge pump, a loop filter, and an FV characteristic adjustment unit setting the FV characteristic. The voltage controlled oscillator has an FV characteristic indicating the relationship between a control signal and a frequency and outputs an oscillation signal having a frequency corresponding to the control signal based on the FV characteristic. The phase comparator detects a phase difference between an input signal and the control signal. The charge pump outputs a corrected voltage value changed according to the phase difference. The loop filter outputs a control voltage value changed in response to corrected voltage value variations. The FV characteristic adjustment unit generates an FV characteristic control signal by a mean corrected voltage value.
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