RFID tag circuits tags and methods for backscattering with controllable admittance
First Claim
1. A Radio Frequency Identification (RFID) Integrated Circuit (IC) chip for use with an RFID tag that has an antenna for receiving an RF wave, the IC chip comprising:
- two nodes defining a chip admittance between them, at least one of the nodes for coupling to the antenna;
a control circuit for outputting a control signal;
a processor for generating a data output signal in response to the received RF wave;
a modulator operable to backscatter the received RF wave by alternating the chip admittance responsive to the data output signal between an ON admittance value of the chip admittance that is associated with an ON-state and an OFF admittance value of the chip admittance that is associated with an OFF-state, in which an admittance difference between the ON admittance value and the OFF admittance value is controlled responsive to the control signal; and
a controllable admittance circuit distinct from the modulator, coupled between the two nodes, in which the control signal is received by the controllable admittance circuit.
1 Assignment
0 Petitions
Accused Products
Abstract
RFID tag circuits, tags, and methods are provided for backscattering a received RF wave using a controllable admittance difference between the ON state and the OFF state. The admittance difference is controlled responsive to a control signal. In some embodiments, the control signal is generated responsive to a command. In others, the control signal is generated responsive to detecting the power level of the received RF wave. In those, the inherent behavior of the admittance difference can be shaped as desired. For example, it can be such that the backscatters with advantageously more power when it is away from the reader, and with less power when it is close to the reader, so as to meet regulatory requirements.
23 Citations
41 Claims
-
1. A Radio Frequency Identification (RFID) Integrated Circuit (IC) chip for use with an RFID tag that has an antenna for receiving an RF wave, the IC chip comprising:
-
two nodes defining a chip admittance between them, at least one of the nodes for coupling to the antenna; a control circuit for outputting a control signal; a processor for generating a data output signal in response to the received RF wave; a modulator operable to backscatter the received RF wave by alternating the chip admittance responsive to the data output signal between an ON admittance value of the chip admittance that is associated with an ON-state and an OFF admittance value of the chip admittance that is associated with an OFF-state, in which an admittance difference between the ON admittance value and the OFF admittance value is controlled responsive to the control signal; and a controllable admittance circuit distinct from the modulator, coupled between the two nodes, in which the control signal is received by the controllable admittance circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
-
-
16. A Radio Frequency Identification (RFID) Integrated Circuit (IC) chip for use with an RFID tag that has an antenna for receiving an RF wave, the IC chip comprising:
-
two nodes defining a chip admittance between them, at least one of the nodes for coupling to the antenna; a control circuit for outputting a control signal; a processor for generating a data output signal in response to the received RF wave; and a modulator operable to backscatter the received RF wave by alternating the chip admittance responsive to the data output signal between an ON admittance value of the chip admittance that is associated with an ON-state and an OFF admittance value of the chip admittance that is associated with an OFF-state, in which an admittance difference between the ON admittance value and the OFF admittance value is controlled responsive to the control signal, and in which the modulator includes; a combiner circuit coupled to receive the data output signal and the control signal, and to output a first capacitance control signal in response thereto; a variable capacitor with a first terminal coupled to one of the nodes, a second terminal coupled to the other one of the nodes, and whose capacitance depends on the first capacitance control signal. - View Dependent Claims (17, 18)
-
-
19. A Radio Frequency Identification (RFID) tag, comprising:
-
an antenna for receiving an RF wave; a chip with two nodes defining a chip admittance between them and coupled to the antenna; a control circuit on the chip for outputting a control signal; a processor on the chip for generating a data output signal in response to the received RF wave; a modulator on the chip operable to backscatter the received RF wave by alternating the chip admittance responsive to the data output signal between an ON admittance value of the chip admittance that is associated with an ON-state and an OFF admittance value of the chip admittance that is associated with an OFF-state, in which an admittance difference between the ON admittance value and the OFF admittance value is controlled responsive to the control signal; and a controllable admittance circuit distinct from the modulator, coupled between the two nodes, and in which the control signal is received by the controllable admittance circuit. - View Dependent Claims (20, 21, 22, 23, 24)
-
-
25. A method for a Radio Frequency Identification (RFID) tag circuit that has two nodes which define a chip admittance between them, comprising:
-
receiving an RF wave from an RFID reader; detecting a power level of the received RF wave, outputting a control signal responsive to the detected power level, in which the control signal is one of;
an analog signal whose level varies based on the power level of the received RF wave, a signal whose frequency varies based on the power level of the received RF wave, a signal based on a peak of the received RF wave, and a signal whose value is based on a logarithm of the power level of the received RF wave;controlling, responsive to the control signal, an admittance difference by controlling one or both of an ON admittance value of the chip admittance that is associated with an ON-state and an OFF admittance value of the chip admittance that is associated with an OFF-state; generating a data output signal in response to the received RF wave; and backscattering the received RF wave by alternating the chip admittance responsive to the data output signal between the ON admittance value and the OFF admittance value. - View Dependent Claims (26, 27, 28, 29, 30)
-
-
31. A Radio Frequency Identification (RFID) Integrated Circuit (IC) chip for use with an RFID tag that has an antenna for receiving an RF wave, the IC chip comprising:
-
two nodes defining a chip admittance between them, at least one of the nodes for coupling to the antenna; a control circuit for outputting a control signal, in which the control circuit includes an RF power level detector circuit operable to detect a power level of the received RF wave and the control signal is one of;
an analog signal whose level varies based on the power level of the received RF wave, a signal whose frequency varies based on the power level of the received RF wave, a signal based on a peak of the received RF wave, and a signal whose value is based on a logarithm of the power level of the received RF wave;a processor for generating a data output signal in response to the received RF wave; and a modulator operable to backscatter the received RF wave by alternating the chip admittance responsive to the data output signal between an ON admittance value of the chip admittance that is associated with an ON-state and an OFF admittance value of the chip admittance that is associated with an OFF-state, in which an admittance difference between the ON admittance value and the OFF admittance value is controlled responsive to the control signal. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
-
Specification