RFID tags
AssigneeCambridge Resonant Technologies Ltd.
InventorNicholas Patrick Roland Hill
Life of this patent
Estimating the term…
Abstract
An RF tag for sending data to a tag reader is described. The tag comprises an antenna to couple to an RF field of the tag reader and first and second resonant circuits, the first comprising a non-linear, adaptive resonator configured to automatically self-tune to a frequency of the RF field, the second a linear resonator. The tag also has a local power store. The tag powers up using the non-linear, adaptive resonator, which can automatically self-tune without an external power supply, and this resonator is used to charge the local power store. Once operational the tag switches to using a linear resonator for communicating with the tag reader.
Claims20
An RF tag for sending data to a tag reader, the tag comprising:
- an antenna to couple to an RF field of the tag reader;
- a first resonant circuit coupled or couplable to said antenna;
- a second, different resonant circuit coupled or couplable to said antenna;
- and
- a switch to couple the first resonant circuit and the second resonant circuit to the antenna;
- and
- a local power store to store power extracted from said RF field for powering said tag;
- wherein said first resonant circuit comprises a non-linear, self-adaptive resonator comprising first and second capacitive paths, each having a respective capacitance, and a component connected to couple said first and second capacitive paths into said first resonant circuit with a variable duty cycle;
- wherein said second resonant circuit comprises a linear resonator for communicating with said tag reader;
- wherein at least said non-linear self-adaptive resonator is coupled to said local power store to charge said local power store using power from said RF field of said tag reader;
- and
- wherein the switch couples said non-linear self-adaptive resonator to said antenna for charging said local power store to power up the tag until a threshold initial charge is stored to the local power store, wherein after a threshold initial charge is stored to the local power store the switch couples, said linear resonator to said antenna for communicating with said tag reader.
An RF tag for sending data to a tag reader, the tag comprising:
- an antenna to couple to an RF field of the tag reader;
- a resonant circuit, coupled to said antenna, wherein said resonant circuit comprises a non-linear, self-adaptive resonator comprising first and second capacitive paths, each having a respective capacitance, and a component connected to couple said first and second capacitive paths into said first resonant circuit with a variable duty cycle;
- wherein said non-linear self-adaptive resonator is coupled to a local power store to charge said local power store using power from said RF field of said tag reader;
- wherein said tag has a first, charging mode of operation in which said non-linear self-adaptive resonator is coupled to said antenna for charging said local power stored until a threshold initial charge is stored to said local power store, and a second, subsequent communicating mode of operation in which said non-linear self-adaptive resonator is coupled to said antenna for communicating with said tag reader;
- wherein said communication comprises half-duplex communication;
- and
- wherein said tag is configured to alternate said first and second modes of operation to communicate with a half-duplex said tag reader.
A method of using an RF tag for sending data to a tag reader, the method comprising:
- coupling said tag to an RF field of a tag reader using an antenna;
- providing a local power store to store power extracted from said RF field for powering said tag;
- extracting power from said RF field using a non-linear self-adaptive resonator comprising one or more non-linear elements configured to automatically self-tune to a frequency of said RF field, the non-linear self-adaptive resonator comprising first and second capacitive paths, each having a respective capacitance, and a component connected to couple said first and second capacitive paths into said first resonant circuit with a variable duty cycle;
- communicating with said tag reader using a linear resonator;
- operating said tag in a first, charging mode of operation in which said non-linear self-adaptive resonator is coupled to said antenna for charging said local power stored
- automatically tuning to said RF field using said non-linear self-adaptive resonator;
- and
- subsequently operating said tag in second, communicating mode of operation in which said linear resonator is coupled to said antenna for communicating with said tag reader.
Dependencies are inferred from the claim text.