Methods and Apparatus for Dynamic Frequency Scaling of Phase Locked Loops for Microprocessors
AssigneeQUALCOMM Incorporated
InventorsLiang Dai, Brandon Wayne Lewis, Jeffrey Todd Bridges, Weihua Chen
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Abstract
A phase-locked loop employing a plurality of oscillator complexes is disclosed. The phase-locked loop includes a clock output and a plurality of oscillator complexes operable to generate output signals. The phase-locked loop further includes control logic which is configured to selectively couple an output signal of one of the plurality of oscillator complexes to the clock output.
Claims18
A phase-locked loop comprising:
- a clock output;
- a plurality of oscillator complexes operable to generate output signals;
- and
- control logic configured to selectively couple an output signal of one of the plurality of oscillator complexes to the clock output.
A phase-locked loop comprising:
- an input for receiving a reference signal;
- a clock output;
- a feedback path for locking a signal in phase with the reference signal;
- a plurality of oscillator complexes operable to generate output signals and separately couple to the feedback path and the clock output;
- and
- control logic configured to selectively couple an output signal of a first one of the plurality of oscillator complexes to the clock output.
A method of varying the frequency of the output of a phase-locked loop comprising:
- inputting a desired frequency at which an output signal of the phase-locked loop should operate;
- decoupling an oscillator complex from a feedback path of the phase-locked loop;
- adjusting a control of the decoupled oscillator complex to generate a signal as output for the phase-locked loop;
- and
- coupling the oscillator complex to the feedback path to lock the signal in phase with a reference signal when the signal has a frequency within a range of the desired frequency.
A method of varying the frequency of the output of a phase-locked loop comprising:
- coupling a first oscillator complex to the output of the phase-locked loop, the first oscillator complex being decoupled from a feedback path of the phase-locked loop;
- inputting a desired frequency at which an output signal of the phase-locked loop should operate;
- powering a second oscillator complex;
- digitally controlling the second oscillator complex to generate a signal in a frequency range containing the desired frequency;
- decoupling the first oscillator complex from the output of the phase-locked loop;
- and
- coupling the second oscillator complex to the output of the phase-locked loop.
Dependencies are inferred from the claim text.