Intermodulation mitigation technique in an RFID system

  • US 7,518,532 B2
  • Filed: 05/26/2005
  • Issued: 04/14/2009
  • Est. Priority Date: 05/26/2005
  • Status: Active Grant
First Claim
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1. A transponder for receiving an interrogation signal from a reader at a first frequency and sending a response signal from the transponder at the first frequency, while mitigating interference effects from an interfering signal at a second frequency, the transponder comprising:

  • an antenna for receiving an interrogation signal from the reader;

    a detector, in electrical communication with the antenna, for detecting and outputting a baseband analog signal representing the interrogation signal received by the antenna;

    a frequency-selective filter, said frequency-selective filter comprising a low-pass filter, in electrical communication with the detector to receive the baseband analog signal output by the detector, for performing frequency-selective filtering of the baseband analog signal to output an analog signal with reduced interference; and

    signal processing circuits, in electrical communication with the frequency-selective filter to receive the analog signal with the reduced interference, for performing signal processing on the analog signal with the reduced interference to extract information from the analog signal with the reduced interference;

    wherein the low-pass filter has a cutoff frequency which is less than a difference between the first frequency and the second frequency.

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