Patent ID: 8896386

Claim:
A calibration device, for calibrating an oscillating frequency of an oscillator, the calibration device comprising: a phase locking device, arranged to track a first reference clock generated by the oscillator until a feedback clock is phase-aligned with the first reference clock, and then arranged to track a second reference clock generated by the oscillator until a phase difference between the second reference clock and the feedback clock is a static phase difference, wherein the feedback clock is generated by dividing an output oscillating signal of the phase locking device by a divisor, wherein a frequency of the second reference clock is different from a frequency of the first reference clock with a frequency difference; an adjusting circuit, arranged to adjust the divisor into an updated divisor to reduce the static phase difference between the second reference clock and the feedback clock; and a calibrating circuit, arranged to calibrate the oscillating frequency of the oscillator according to the updated divisor corresponding to the frequency difference.