| CPC H03L 7/0991 (2013.01) [G01C 19/567 (2013.01); H03L 7/085 (2013.01)] | 20 Claims |

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1. A phase locked loop comprising:
an oscillator that varies a frequency according to a control signal;
a resonance element that resonates at a predetermined resonance frequency and output a signal obtained by shifting a phase of an output signal of the oscillator by 90 degrees at the resonance frequency;
a phase detector that detects a phase error between an output signal of the resonance element and an output signal of the oscillator;
a feedback controller that controls a frequency of an output signal of the oscillator by proportional control and integral control according to the phase error; and
a control signal corrector that corrects the control signal by adding a correction term corresponding to environment information to an output signal of the feedback controller.
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