| 摘要 |
The voltage-controlled oscillator generates a first signal and a second signal having a phase reverse to that of the first signal, frequencies thereof being controlled depending on control voltages. The sub-sampling phase comparator generates first/second sampled voltages by sampling voltages of the first/second signals in each cycle of the reference signal having cycles. The current generating circuit has first/second charge pumps configured to generate first/second current signal depending on supply voltages, the second current signal having a polarity reverse to that of the first current signal. The selection controller selectively carries out a first supply mode for supplying the first and second sampled voltages to the second and first charge pumps and a second supply mode for supplying the first and second sampled voltages to the first and second charge pumps respectively. The loop filter generates the control voltages supplied to the voltage-controlled oscillator by smoothing the composite current signal. |
