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Digital PLL with hybrid phase/frequency detector and digital noise cancellation

  • US 9,319,051 B2
  • Filed: 05/21/2014
  • Issued: 04/19/2016
  • Est. Priority Date: 05/28/2013
  • Status: Active Grant
First Claim
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1. A phase locked-loop (PLL) comprising:

  • a digitally controlled oscillator (DCO) configured to generate a DCO output frequency in response to a tuning input;

    a frequency reference oscillator configured to generate a reference frequency input;

    a mixed analog/digital signal Delta-Sigma (Δ

    Σ

    ) Phase/Frequency Detector (Δ

    Σ

    PFD) configured to generate a digital output of frequency difference between the reference frequency input and the DCO frequency output, the Δ

    Σ

    PFD comprising;

    a digital requantizer configured to change a quantization resolution of a feedback portion of the digital output; and

    a feedback path configured to receive the feedback portion after the quantization resolution is changed;

    an accumulator configured to generate digital phase and frequency error information by accumulating the Δ

    Σ

    PFD digital output combined with a digital indicator of a targeted output frequency for the DCO; and

    a loop filter following the accumulator and configured to tune phase/frequency of the DCO in response to digital phase and frequency error information.

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