Nova Patents
US20120249303A1

Subset selection of rfid tags using light

Claim Score by NHIP

Read claim 75, the broadest

Abstract

Methods and apparatuses for selecting a subset of RFID tags are provided in some embodiments. These methods and apparatuses utilize the susceptibility to light by persistent nodes found in passive tags. Light can be used to intentionally reduce persistence times in a particular subset tags or even an individual tag. Then, persistent nodes can be used as a selection criterion to distinguish previously illuminated tags from non-illuminated tags. In other embodiments, a power circuit receives a RF input source and generates a direct current (DC) output voltage. The circuit includes a bias circuit to supply a gate to source bias, which is independent of the DC output voltage. The circuit further includes a voltage multiplier circuit that is coupled to the bias circuit. The voltage multiplier circuit has MOS transistors with one transistor to receive the gate to source bias.

US20120249303A1, drawing sheet 1
Sheet 1 of 25

Term

4.9 yearsto projected expiry

Projected expiry 29 August 2031, counted from filing; an application has no term until it is granted.

  1. Priority
  2. Filed
  3. Published
  4. Today
  5. Projected expiry

75 claims: 15 independent, 60 dependent

  1. 1
    A radio frequency identification (RFID) system comprising:a tag with an integrated circuit having at least one flag, the at least one flag having a persistence time reduced by exposure to light;an RFID reader;and a light source configured to reduce the persistence time.
  2. 11
    A radio frequency identification (RFID) reader comprising:a radio frequency source;an antenna to transmit radio frequency waves generated by the radio frequency source;and a light source to produce light rays that manipulate a function of an RFID tag.
  3. 20
    A radio frequency identification (RFID) reader comprising:a radio frequency source;an antenna to transmit radio frequency waves generated by the radio frequency source;and a light source to transmit light waves that manipulate a function of an RFID tag, wherein the antenna transmits radio frequency waves to a first area and the light source transmits to a second area, the second area being a proper subset of the first area.
  4. 22
    A method for selecting a subset of radio frequency identification (RFID) tags comprising:setting a persistent node for each of the plurality of passive tags to a first logic value, the node capable of maintaining the first logic value for a first time period in the absence of power;interrupting power to the passive tag for a second time period, the second time period being shorter than the first time period;and illuminating a subset of the plurality of tags with light during at least a portion of the second time period, persistent nodes of the subset degenerating to a second logic value during the second time period.
  5. 31
    A method for selecting a subset of radio frequency identification (RFID) tags comprising:broadcasting an interrogating signal to set a persistent node for each of the plurality of passive tags to a first logic value, the node capable of maintaining the first logic value for a first time period in the absence of power;interrupting power to the passive tag for a second time period by ceasing the broadcasting, the second time period being shorter than the first time period;and illuminating a subset of the plurality of tags with an illuminating source during at least a portion of the second time period, persistent nodes of the subset degenerating to a second logic value during the second time period, wherein the interrogating signal is a broad beam relative to the narrow beam of the illuminating source.
  6. 32
    A radio frequency identification (RFID) tag comprising:RF circuitry to receive and transmit RF signals to an RFID reader;processing logic coupled to the RF circuitry;a first persistent node coupled to the RF circuitry, the first persistent node being configured to be sensitive to light radiation;and a second persistent node coupled to the RF circuitry, the second persistent node being configured to be less sensitive to light radiation than the first persistent node.
  7. 34
    A circuit to provide a power supply, comprising:a first bias circuit to supply a gate to source bias, which is independent of a direct current (DC) output voltage;a voltage multiplier circuit coupled to the first bias circuit, the voltage multiplier circuit having at least one n-channel metal-oxide-semiconductor (NMOS) transistor with the voltage multiplier circuit to generate the DC output voltage for powering a RF identification tag, the first bias circuit to receive a RF input source and generate the gate to source bias for a gate terminal of a NMOS transistor.
  8. 41
    A multi-stage voltage multiplier circuit, comprising:a first stage of the multi-stage voltage multiplier circuit comprising: a first bias circuit having no effective load;a first voltage multiplier circuit coupled to the first bias circuit, the first voltage multiplier circuit having at least one n-channel metal-oxide-semiconductor (NMOS) transistor with the first voltage multiplier circuit to generate a direct current (DC) output voltage, the first bias circuit to receive a RF input source and generate a gate to source bias for a gate terminal of a NMOS transistor of the first voltage multiplier circuit.
  9. 46
    A demodulator circuit, comprising:a first bias circuit to supply a gate to source bias;a first clamping transistor coupled to the first bias circuit;and a voltage multiplier circuit coupled to the clamping transistor, the voltage multiplier circuit having at least one n-channel metal-oxide-semiconductor (NMOS) transistor with the voltage multiplier circuit to generate a demodulated output signal that demodulates information carried by a RF input signal, the first bias circuit to receive the RF input signal and generate the gate to source bias for a gate terminal of a NMOS transistor, the first clamping transistor to limit a value of the gate to source bias to approximately one threshold voltage of the first clamping transistor or less.
  10. 51
    A circuit to provide a power supply, comprising:a first bias circuit to supply a gate to source bias, which is independent of a direct current (DC) output voltage;and a voltage multiplier circuit coupled to the first bias circuit, the voltage multiplier circuit having at least one p-channel metal-oxide-semiconductor (PMOS) transistor with the voltage multiplier circuit to generate the DC output voltage for powering a RF identification tag, the first bias circuit to receive a RF input source and generate the gate to source bias for a gate terminal of a PMOS transistor.
  11. 54
    A radio frequency identification (RFID) tag comprising:RF circuitry to receive and transmit RF signals to a RFID reader;processing logic coupled to the RF circuitry;and a persistent node coupled to the RF circuitry, the persistent node being configured to be relatively insensitive to light radiation, the persistent node having at least one transistor with a base region of the transistor being isolated with a well implant.
  12. 62
    A radio frequency identification (RFID) tag comprising:RF circuitry to receive and transmit RF signals to an RFID reader;processing logic coupled to the RF circuitry;and an oscillator coupled to the RF circuitry, the oscillator being configured to be relatively insensitive to light radiation, the oscillator having at least one transistor with a base region of the transistor being isolated with a well implant.
  13. 70
    A radio frequency identification (RFID) tag comprising:RF circuitry to receive and transmit RF signals to an RFID reader;processing logic coupled to the RF circuitry;and an oscillator coupled to the RF circuitry, the oscillator being configured to be relatively insensitive to light radiation, the oscillator configured to vary its oscillation frequency with temperature.
  14. 74
    A multi-stage voltage multiplier circuit, comprising:a NMOS transistor and a RF powered circuit which supplies a bias for said NMOS transistor, where the output of the multiplier circuit exceeds 1 microamp at a output voltage of 0.7 volts, with an input RF amplitude of 190 millivolts RMS.
  15. 75
    Broadest claimClaim Score 88, very broad(NHIP)A passive RFID tag comprising a voltage multiplier circuit which provides sufficient power to power circuitry of the tag with an input RF amplitude of 190 millivolts RMS.
Independent claims15