Digitally-synthesized loop filter circuit particularly useful for a phase locked loop

  • US 6,765,445 B2
  • Filed: 09/05/2003
  • Issued: 07/20/2004
  • Est. Priority Date: 07/10/2000
  • Status: Expired due to Term
First Claim
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1. In a phase locked loop system, a digitally-synthesized loop filter circuit comprising:

  • a first circuit for providing a digital representation of a phase error signal of the phase locked loop;

    a second circuit responsive to the digital phase error signal, for generating a multi-bit accumulated digital phase error signal representing an accumulated value of successive values of the digital phase error signal; and

    a third circuit for generating an output signal corresponding to the accumulated digital phase error signal, said output signal useful for controlling an oscillator within the phase locked loop.

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