Patent ID: 6614866
Filing Date: 2003-09-02
Classification: H03L

Abstract:
A phase locked loop, comprising:a phase detector having as inputs a reference frequency signal and a feedback signal, the phase detector being operable to generate a phase detection signal based on a comparison of phases between the reference frequency signal and the feedback signal; a loop filter coupled to the phase detector for receiving the phase detection signal and for generating an output voltage in response to the phase detection signal; a voltage controlled oscillator coupled to the output voltage of the loop filter for generating a local oscillator signal; and a feedback circuit coupled to the local oscillator signal for generating the feedback signal, the feedback circuit comprising a sampling circuit, the sampling circuit being operable to sample the local oscillator signal with a sampling frequency that is substantially less than the frequency of the local oscillator signal to generate a sampling circuit output signal, the sampling circuit output signal comprising a beat frequency signal having a beat frequency that is equal to the frequency difference between the frequency of the local oscillator signal and the nearest harmonic of the sampling frequency, and wherein the feedback signal is derived from the beat frequency signal.