Patent ID: 7630698
Filing Date: 2009-12-08
Classification: H03L

Abstract:
1. A phase locked loop comprising: a first phase/frequency detector and a second phase/frequency detector, each having two inputs and one output; a first charge pump coupled to the output of the first phase/frequency detector; a second charge pump coupled to the output of the second phase/frequency detector; a first loop filter coupled to an output of the first charge pump and coupled to a first tuning port of a voltage controlled oscillator; a second loop filter coupled to an output of the second charge pump and coupled to a second tuning port of a voltage controlled oscillator; the voltage controlled oscillator having an output that is coupled to the first and second phase/frequency detectors, and having first and second tuning ports with low leakage, wherein a charge accumulated in the second loop filter coupled between the second phase/frequency detector and the second tuning port does not discharge while the second tuning port is deactivated; and control circuitry, responsive to an input switch signal, configured to cause the voltage controlled oscillator to either