Single chip RF tag oscillator circuit synchronized by base station modulation frequency

CAFC
  • US 5,912,632 A
  • Filed: 01/08/1997
  • Issued: 06/15/1999
  • Est. Priority Date: 01/08/1997
  • Status: Expired due to Term
First Claim
Patent Images

1. A passive radio frequency (RF) transponder (tag) for receiving an RF signal from a base station, comprising;

  • a tag antenna for receiving the RF signal fron the base station the RF signal having a carrier frequency;

    a tag rectification power supply connected to the tag antenna;

    a tag logic section and a tag memory section the tag logic section and the tag memory section receiving power only from the tag antenna through the tag rectification power supply;

    a receiver section connected to the tag antenna; and

    a tag oscillator connected to the receiver section, the tag oscillator having a plurality of possible discrete frequencies of oscillation, the tag oscillator having a tag oscillation frequency much less than the carrier frequency, the tag oscillator frequency used to determine a tag modulation frequency of an RF signal backscattered from the tag antenna, the tag oscillation frequency determined by the RF signal sent from the base station.

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