RFID tags
AssigneeCambridge Resonant Technologies Ltd.
InventorNicholas Patrick Roland Hill
Life of this patent
Estimating the term…
Abstract
We describe RFID tags that incorporate a nonlinear resonator that self-adapts to the driving frequency of a reader. More particularly we describe an RF tag for sending data to a tag reader by modulating energy drawn from an RF field of said tag reader, the tag comprising: an antenna; a resonant circuit coupled to said antenna to resonate at a frequency of said RF field; a local power store to store power extracted from said RF field; a modulation system to modulate one or both of the resonance amplitude and a relative phase of a signal in said resonant circuit with respect to said RF field; and a feedback circuit coupled to said resonant circuit and to said local power store to control one or both of said resonance amplitude and said relative phase to control transients in said resonance amplitude caused by said modulation.
Claims43
A full-duplex RF tag for sending data to a tag reader by load modulation of an RF field of said tag reader, the tag comprising:
- an antenna to couple to said RF field of said tag reader;
- a resonant circuit coupled to said antenna to resonate at a frequency of said RF field with a resonance amplitude;
- a local power store to store power extracted from said RF field;
- a modulation system to provide said load modulation by modulating one or both of said resonance amplitude and a relative phase of a signal in said resonant circuit with respect to said RF field;
- and
- a feedback circuit coupled to said resonant circuit and to said local power store to control one or both of said resonance amplitude and said relative phase to control transients in said resonance amplitude caused by said modulating to provide said load modulation, wherein
- said feedback circuit is arranged to draw power from the resonant circuit and store the drawn power in said local power store during said load modulation, said drawing of power to control a first modulation transition of said resonance, and is further arranged to draw power from said local power store during said load modulation to control a second, opposite-going modulation transition of said resonance, wherein said first and second modulation transitions are for said load modulation and are each between two data states of said modulating.
A full-duplex RF tag for receiving data from a tag reader modulating an RF field, the RF tag comprising:
- an antenna to couple to said RF field of said tag reader;
- a resonant circuit coupled to said antenna to resonate at a frequency of said RF field with a resonance amplitude;
- a local power store to store power extracted from said RF field;
- a feedback circuit coupled to said resonant circuit and to said local power store to control one or both of said resonance amplitude and said relative phase to control transients in said resonance amplitude caused by said modulation by said tag reader;
- and
- an output from one or both of said resonant circuit and said feedback circuit to output a signal dependent on said data modulating said RF field, wherein
- said feedback circuit is arranged to draw power from the resonant circuit and store the drawn power in said local power store during said modulation, said drawing of power to control a first modulation transition of said resonance, and is further arranged to draw power from said local power store during said modulation to control a second, opposite-going modulation transition of said resonance, wherein said first and second modulation transitions are each between two data states of said modulating.
A full-duplex RF tag for sending data to a tag reader by load modulation of an RF field of said tag reader, the tag comprising:
- an antenna to couple to said RF field of said tag reader;
- a resonant circuit coupled to said antenna to resonate at a frequency of said RF field with a resonance amplitude;
- a local power store to store power extracted from said RF field;
- a modulation system to provide said load modulation by modulating one or both of said resonance amplitude and a relative phase of a signal in said resonant circuit with respect to said RF field;
- and
- wherein said modulating comprises amplitude modulation;
- and
- wherein said tag further comprises a system to use said local power store to assist an increase in said resonance amplitude during said amplitude modulation, wherein
- said feedback circuit is arranged to draw power from the resonant circuit and store the drawn power in said local power store during said load modulation, said drawing of power to control a first modulation transition of said resonance, and is further arranged to draw power from said local power store during said load modulation to control a second, opposite-going modulation transition of said resonance, wherein said first and second modulation transitions are for said load modulation and are each between two data states of said modulating.
A full duplex RF tag for load modulating an RF field to provide a modulated data return to a tag reader, said tag comprising a resonant circuit including at least one capacitor, and wherein said resonant circuit includes a resonance regeneration system such that during amplitude modulation of a resonant signal in said resonant circuit, when an amplitude of said resonant signal is reduced energy from said reduction is stored to control a first modulation transition of said resonance and when said amplitude is increased said stored energy is used to regenerate said resonant signal to control a second, opposite-going modulation transition of said resonance, wherein said first and second modulation transitions are each between two data states of said load modulating.
Dependencies are inferred from the claim text.