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Homodyne RFID receiver and method

  • US 7,209,040 B2
  • Filed: 11/19/2004
  • Issued: 04/24/2007
  • Est. Priority Date: 11/19/2004
  • Status: Active Grant
First Claim
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1. An RFID circuit comprising:

  • an RF carrier signal source;

    a hybrid coupled to the RF carrier signal source operable to generate first and second phase-shifted RF carrier signals;

    first and second mixers coupled to the hybrid each operable to multiply a respective one of the first and second carrier signals and a received backscattered modulated carrier signal and generate first and second baseband signals, respectively; and

    first logic coupled to the first and second mixers operable to select one of the first and second baseband signals having a larger amplitude as a demodulated RFID output signal, further includes;

    second logic coupled to the first and second mixers and operable to determine whether the first and second baseband signals have the same polarity;

    third logic coupled to the first and second mixers and operable to determine which of the first and second baseband signals have a larger amplitude; and

    fourth logic coupled to the third logic operable to determine when signal having larger amplitude is switching from the first baseband signal to the second, and vice versa.

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