Analog phase-locked oscillator that prevents leakage of harmonics

摘要

There are provided a voltage-controlled oscillator whose oscillation frequency is controlled by a control voltage, a reference oscillator, and a sampling phase detector for receiving an oscillation signal of the voltage-controlled oscillator and a reference oscillation signal of the reference oscillator and for inputting, to the voltage-controlled oscillator, as the control voltage, an error voltage that is obtained on the basis of a phase difference between the oscillation signal and a harmonic of the reference oscillation signal. An irreversible circuit element is provided between the voltage-controlled oscillator and the sampling phase detector. The oscillation signal that is output from the voltage-controlled oscillator is input to the sampling phase detector via the irreversible circuit element.