Patent attributes
A frequency synthesizer with automatic calibration includes a voltage-controlled oscillator, which has several working bands for receiving a coarse-tuned signal and a fine-tuned signal and generating an output signal in the working band of the coarse-tuned signals; preliminary frequency divider unit, which receives the output signal and generates an intermediate signal by frequency dividing; a feedback frequency divider unit, which receives the intermediate signal and generates a feedback signal by frequency dividing; an automatic calibration unit, which receives the input signal and the intermediate signal to generate a coarse-tuned signal; a phase-frequency comparator, which compares the input signal with the feedback signal and generates an error signal according to the frequency and phase differences between the input signal and the feedback signal; and a low-pass filter, which filters the error signal and generates a fine-tuned signal.
