Patent ID: 6091303
Filing Date: 2000-07-18
Classification: H03C,H03L,H04L

Abstract:
A circuit for reducing phase noise in a transmitted radio signal comprising:a first phase-locked loop circuit including a first controlled oscillator generating a first output signal at a first desired frequency, and a first phase comparator developing a first phase error signal to control the first controlled oscillator, the first phase error signal being representative of phase differences between the first output signal and a reference signal;a second phase-locked loop circuit including a second controlled oscillator generating a second output signal at a desired frequency of transmission related to the first desired frequency, and a second phase comparator developing a second phase error signal representative of phase differences between the second output signal and the first output signal; anda summer combining the first and second error signals to control the second controlled oscillator to thereby reduce phase noise generated by the first controlled oscillator in the second output signal transmitted as a radio signal at the desired frequency of transmission.