Digitally controlled analog frequency synthesizer

摘要

A frequency synthesizer according to the present invention digitally controls an analog oscillator to generate an analog output signal at a desired frequency. A digitizing circuit converts a feedback signal derived from the oscillator output signal to a digitized multi-phase feedback signal. A comparator compares the digitized multi-phase feedback signal to a reference signal generated by the reference signal generator to generate an error signal indicative of the phase error in the output signal. A control circuit generates a control signal based on the error signal to control the frequency of the oscillator output signal.