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Automatic selection of an operating frequency in a low-gain broadband phase lock loop system

  • US 5,382,921 A
  • Filed: 11/23/1992
  • Issued: 01/17/1995
  • Est. Priority Date: 11/23/1992
  • Status: Expired due to Term
First Claim
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1. A phase-lock loop system for automatically frequency-locking a signal in phase with a reference signal, said system comprising:

  • a. a reference source for providing a reference signal;

    b. a phase and frequency detector for comparing said reference signal to said signal, said phase and frequency detector coupled to said reference source;

    c. an up/down counter coupled to said phase and frequency detector;

    d. a digital-to-analog converter for providing an analog control signal, said digital-to-analog converter coupled to said up/down counter;

    e. a decoder for providing a digital control signal, said decoder coupled to said up/down counter; and

    f. a ring oscillator having a plurality of stages connected in tandem, said ring oscillator coupled to said digital-to-analog converter and to said decoder, said ring oscillator having a digital input for receiving said digital control signal and an analog input for receiving said analog control signal, wherein each of said plurality of stages of said ring oscillator includes an anti-high gain circuit.

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