Advanced spread spectrum clock generation technique for EMI reduction of multiple clock sources
AssigneeDell Products L.P.
InventorJeffery Charles Hailey
Life of this patent
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Abstract
The present invention describes a method and apparatus for reducing EMI emission in a multi source electronic system. The phase of the modulated waveform is varied to minimize the number of clocks within the EMI measurement bandwidth. The phase of the modulated waveform is varied in proportion to the number of EMI generating sources in the electronic system. The spread-spectrum clock is used as reference for phase delay of the modulated waveform. The phase delay can be predetermined or dynamically programmed according to the number of the EMI sources in the electronic system.
Claims21
A method of reducing electromagnetic interference in a system comprising:
- generating a spread-spectrum master clock;
- dynamically calculating a plurality of phase delays;
- generating a plurality of phase-offset spread-spectrum slave clocks from said spread-spectrum master clock, the clocks having the dynamically calculated phase delays;
- and
- using said plurality of phase-offset spread-spectrum slave clocks for a plurality of electromagnetic interference sources.
A system for reducing electromagnetic interference comprising:
- a spread-spectrum clock generator, said spread-spectrum clock generator generates a spread-spectrum master clock;
- and
- a phase delay unit coupled to said spread-spectrum clock generator, said phase delay unit provides a dynamically determined phase delay for said spread-spectrum master clock.
A system for reducing electromagnetic interference comprising:
- means for generating a spread-spectrum master clock;
- means for generating a dynamically-calculated plurality of phase-offset spread-spectrum slave clocks from said spread-spectrum master clock;
- and
- means for using said plurality of phase-offset spread-spectrum slave clocks for a plurality of electromagnetic interference sources.
An information handling system comprising:
- a processor;
- a system bus;
- a memory coupled to said processor via said system bus, said processor is configured to
- generate a spread-spectrum master clock;
- generate a plurality of spread-spectrum slave clocks from said spread-spectrum master clock, the spread-spectrum slave clocks having substantially evenly spaced phases;
- and
- use said plurality of phase-offset spread-spectrum slave clocks for a plurality of electromagnetic interference sources.
Dependencies are inferred from the claim text.