Methods and circuits for frequency modulation that reduce the spectral noise of switching regulators
AssigneeLinear Technology Corporation
InventorsYuhui Chen, Doug LaPorte, Randy Guy Flatness, Robert C. Dobkin
Life of this patent
Estimating the term…
Abstract
The present invention comprises methods and circuits for spread spectrum frequency modulation that reduce peak spectral noise at the outputs or inputs of switching regulators. More specifically, the present invention modulates the operating frequency of the switching regulator in accordance with a frequency modulation waveform having a shape coordinated to a peak noise amplitude waveform that describes the correlation between the operating frequency of a switching regulator and the peak noise amplitude at the regulator's input or output absent spread spectrum frequency modulation.
Claims39
A circuit for reducing peak spectral noise of a switching regulator, wherein a noise spectrum having a spectral ceiling may be generated, the circuit comprising:
- a signal generator that generates a varying signal, the signal generator configured to vary the varying signal to form a signal waveform over time;
- and
- an oscillator that generates a clock signal using the varying signal to modulate a frequency of the clock signal in accordance with a frequency modulation waveform,
- wherein the frequency modulation waveform is a function of time and has a shape that is coordinated to a peak noise amplitude waveform.
The circuit of claim of 1, wherein the frequency modulation waveform has a shape that substantially flattens the spectral ceiling.
A method for reducing peak spectral noise of a switching regulator, wherein a noise spectrum having a spectral ceiling may be generated, the method comprising:
- generating a clock signal having a frequency;
- and
- modulating the frequency of the clock signal in accordance with a frequency modulation waveform in a spread spectrum mode,
- wherein the frequency modulation waveform is a function of time and has a shape coordinated to a peak noise amplitude waveform.
Dependencies are inferred from the claim text.