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Programmable phase shift and duty cycle correction circuit and method

  • US 7,138,841 B1
  • Filed: 12/16/2004
  • Issued: 11/21/2006
  • Est. Priority Date: 12/23/2003
  • Status: Active Grant
First Claim
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1. A circuit configured for generating an output signal in response to an input signal, the circuit comprising:

  • a storage device configured for generating a linearly increasing voltage signal when charged;

    series-coupled current source and switch further coupled in series with the storage device for charging the storage device when the switch is closed;

    a programmable digital-to-analog converter (DAC) configured for generating an adjustable reference voltage;

    a comparator having a pair of inputs, one coupled to the storage device and one to the programmable DAC, wherein the comparator is configured for transitioning the output signal from logic LOW to logic HIGH once the linearly increasing voltage exceeds the adjustable reference voltage, and wherein a phase difference between the input and output signals is determined, at least in part, by the adjustable reference voltage; and

    a delay sub-circuit coupled for receiving the input signal and configured for generating a discharge signal on each rising edge of the input signal.

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