US Patent 8427243 Signal generating circuit and signal generating method

A signal generating circuit includes: an operating circuit arranged to generate a first control signal according to a reference clock signal and a feedback oscillating signal; a controllable oscillator arranged to generate an output oscillating signal according to the first control signal and a second control signal; a feedback circuit arranged to generate the feedback oscillating signal according to the output oscillating signal and a third control signal; a control circuit arranged to generate the second control signal and the third control signal according to an input signal; and a calibrating circuit arranged to calibrate the control circuit to adjust the second control signal by detecting a phase difference between the reference clock signal and the feedback oscillating signal.