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Complex-IF digital receiver

  • US 7,173,980 B2
  • Filed: 09/20/2002
  • Issued: 02/06/2007
  • Est. Priority Date: 09/20/2002
  • Status: Expired due to Term
First Claim
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1. A receiver comprising:

  • an in-phase mixer configure to translate an incoming signal to an in-phase intermediate frequency signal;

    an in-phase delta-sigma modulator configured to convert the in-phase intermediate frequency signal into an in-phase digital signal at a predetermined sampling rate;

    an in-phase decimation filter configured to decimate the in-phase digital signal;

    a quadrature mixer configured to translate an incoming signal to an quadrature intermediate frequency signal;

    a quadrature delta-sigma modulator configured to convert the quadrature intermediate frequency signal into a quadrature digital signal at a predetermined sampling rate;

    wherein the quadrature delta-sigma modulator is configured to operate independent of the output of the in-phase delta-sigma modulator and the in-phase delta-sigma modulator is configured to operate independent of the output of the quadrature delta-sigma modulator;

    a quadrature decimation filter configured to decimate the quadrature digital signal;

    a translation circuit configured to translate the decimated in-phase and quadrature digital signals to in-phase and quadrature baseband digital signals; and

    a voltage controlled oscillator;

    wherein each of the in-phase and quadrature mixers translates the incoming signal by a local oscillator frequency of fLO derived from the voltage controlled oscillator; and

    the sampling rate of each of the in-phase and quadrature delta-sigma modulators is derived from the voltage controlled oscillator and equal to an integer sub-multiple of fLO; and

    wherein each of the in-phase and quadrature intermediate frequency signals has an intermediate frequency equal to fLO divided by an integer that is a function of a decimation ratio of the each of the in-phase and quadrature decimation filters.

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