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Direct digital synthesizer driven phase lock loop frequency synthesizer

  • US 4,965,533 A
  • Filed: 08/31/1989
  • Issued: 10/23/1990
  • Est. Priority Date: 08/31/1989
  • Status: Expired due to Term
First Claim
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1. An apparatus for synthesizing frequencies, comprising:

  • variable reference means for generating a periodic signal of a frequency selected from a plurality of reference frequencies, said variable reference means comprising,phase accumulator means for, receiving a digital frequency control signal indicative of a selected phase increment value, receiving an externally generated clock signal, accumulating phase increment values at a rate corresponding to said clock signal, and providing an accumulator output signal corresponding to said accumulated phase increment values;

    memory means for storing a plurality of amplitude values each corresponding to a respective accumulated phase increment value, receiving said accumulator output signal and providing a memory output signal indicative of the amplitude value corresponding to each accumulated phase increment value of said accumulator output signal; and

    converter means for, receiving said memory output signal converting said received memory output signal to an analog amplitude signal corresponding to said memory output signal amplitude values, and providing said analog amplitude signal as said periodic signal; and

    frequency tuning means for receiving said periodic signal and generating an output signal of a frequency which is a multiple of said periodic signal frequency.

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