Barry Travis Hunt

US Patent:

20060170505, Aug 3, 2006

Filed:

Jan 31, 2005

Appl. No.:

11/047258

Inventors:

Scott Humphreys - Greensboro NC, US
Ryan Bunch - Greensboro NC, US
Barry Hunt - Greensboro NC, US
Alexander Wayne Hietala - Phoenix AZ, US

Assignee:

RF MICRO DEVICES, INC. - Greensboro NC

International Classification:

H03L 7/00

US Classification:

331016000

Abstract:

A fractional-N offset phase locked loop (FN-OPLL) is provided. The FN-OPLL includes a fractional divider, a phase detector, a loop filter, a voltage controlled oscillator (VCO), and feedback circuitry. Combiner circuitry combines an initial fractional divide value and a modulation signal to provide a combined fractional divide value. Based on the combined fractional divide value, the fractional-N divider divides a reference frequency and provides a divided reference frequency to the phase detector. The phase detector compares a phase of the divided reference frequency to a phase of a feedback signal to provide a comparison signal. The comparison signal is filtered by the loop filter to provide a control signal to the VCO, where the control signal controls a frequency of an output signal of the VCO. The output signal is processed by the feedback circuitry to provide the feedback signal to the phase detector.