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Differential radio frequency identification reader

  • US 7,014,103 B2
  • Filed: 06/14/2004
  • Issued: 03/21/2006
  • Est. Priority Date: 06/13/2003
  • Status: Active Grant
First Claim
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1. A differential radio frequency identification reader for producing a signal resulting from effects caused by a radio frequency identification (RFID) tag to be read, comprising:

  • a transmit coil for emitting a transmit field to power and interrogate a transponder;

    a receive coil for sensing changes in the transmit field resulting from effects caused by the RFID tag;

    a reference coil effectively isolated from the RFID tag and operating to sense the transmit field unaffected by the RFID tag; and

    a differential amplifier for receiving inputs from the receive coil and the reference coil, the differential amplifier being operative to amplify a difference of said inputs thereby producing an amplified output signal reflecting the changes in the transmit field caused by the RFID tag.

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