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Coarse tuning for fractional-N synthesizers

  • US 7,274,229 B1
  • Filed: 06/22/2006
  • Issued: 09/25/2007
  • Est. Priority Date: 05/11/2004
  • Status: Expired due to Fees
First Claim
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1. A fractional-N frequency synthesizer comprising:

  • a phase lock look (PLL);

    coarse tuning circuitry coupled to the PLL and adapted to control the PLL such that the PLL operates in an integer division mode during coarse tuning and a fractional-N division mode during normal operation;

    wherein the coarse tuning circuitry comprises divide value generation circuitry adapted to;

    provide an integer divide value to a divider of the PLL when operating in the integer division mode; and

    provide a fractional sequence of divide values to the divider of the PLL when operating in the fractional-N division mode,wherein the integer divide value includes an integer component of a product of a desired N value and a modulus M.

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