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Spread spectrum modulation of a clock signal for reduction of electromagnetic interference

  • US 20070216488A1
  • Filed: 03/03/2006
  • Published: 09/20/2007
  • Est. Priority Date: 03/03/2006
  • Status: Active Grant
First Claim
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1. A spread spectrum frequency modulated oscillator circuit, comprising:

  • a reference component;

    a controlled oscillator;

    a first circuit coupled to the reference component and controlled oscillator and configured to supply a first control signal to the oscillator to cause the oscillator to oscillate at a frequency corresponding to a value of the reference component;

    a second circuit configured to supply a random signal to the oscillator to cause the frequency of the oscillator to dither; and

    a third circuit configured to control (1) a rate of change of the oscillator frequency such that the rate of change is a fixed percentage of the oscillator frequency, and (2) an amount of frequency change in the oscillator frequency such that the amount of frequency change is a fixed percentage of the oscillator frequency.

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