SYSTEMS AND METHODS TO SELECTIVELY CONNECT ANTENNAS TO RECEIVE AND BACKSCATTER RADIO FREQUENCY SIGNALS
First Claim
1. A radio frequency identification (RFID) system, comprising:
- an RFID reader having a plurality of reader antennas of different polarizations to transmit radio frequency signals; and
at least one RFID tag, the RFID tag comprisinga plurality of tag antennas of different polarizations,a plurality of diodes coupled to the plurality of tag antennas respectively,a receiver coupled to the plurality of diodes to receive the radio frequency signals from the tag antennas when the diodes are forward biased, anda set of one or more current controllers coupled to the plurality of diodes, in a receiving mode the set of current controllers to forward bias at least one of the diodes to receive signals from the RFID reader, in a transmitting mode the set of current controllers to change a backscatter state of at least one of the tag antennas to transmit data via backscattering the radio frequency signals.
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Accused Products
Abstract
Systems and methods to selectively attach and control antennas via diodes and current sources. In one embodiment, a system includes: an RFID reader having a plurality of reader antennas of different polarizations to transmit radio frequency signals; and at least one RFID tag. The RFID tag includes: a plurality of tag antennas of different polarizations; a plurality of diodes coupled to the plurality of tag antennas respectively; a receiver coupled to the plurality of diodes to receive the radio frequency signals from the tag antennas when the diodes are forward biased; and a set of one or more current controllers coupled to the plurality of diodes. In a receiving mode the controllers selectively forward bias the diodes to receive the signals from the RFID reader. In a transmitting mode the controllers selectively change the state of the tag antennas to transmit data via backscattering the radio frequency signals.
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Citations
21 Claims
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1. A radio frequency identification (RFID) system, comprising:
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an RFID reader having a plurality of reader antennas of different polarizations to transmit radio frequency signals; and at least one RFID tag, the RFID tag comprising a plurality of tag antennas of different polarizations, a plurality of diodes coupled to the plurality of tag antennas respectively, a receiver coupled to the plurality of diodes to receive the radio frequency signals from the tag antennas when the diodes are forward biased, and a set of one or more current controllers coupled to the plurality of diodes, in a receiving mode the set of current controllers to forward bias at least one of the diodes to receive signals from the RFID reader, in a transmitting mode the set of current controllers to change a backscatter state of at least one of the tag antennas to transmit data via backscattering the radio frequency signals. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A radio frequency identification (RFID) tag, comprising:
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a receiver; a plurality of antennas; a plurality of diodes coupled between the plurality of antennas and the receiver, the diodes to provide signal paths between the antennas and the receiver when the diodes are forward biased; and a plurality of current controllers coupled to the plurality of diodes respectively, the current controllers controllable to selectively forward bias the diodes and to selectively ground the antennas to modulate backscatter by the antennas. - View Dependent Claims (8, 9, 10, 11)
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12. A radio frequency identification (RFID) tag, comprising:
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a receiver; a plurality of antennas; a plurality of diodes coupled between the plurality of antennas and the receiver; and a transistor coupled to the plurality of diodes, when in a receiving mode the transistor to provide a current to forward bias the diodes, when forward biased the diodes to provide signals from the antennas to the receiver, when in a transmitting mode the transistor to selectively ground the antennas to modulate backscatter by the antennas. - View Dependent Claims (13, 14)
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15. A radio frequency device, comprising:
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an antenna; a receiver; a diode coupled between the antenna and the receiver, when forward biased the diode to provide radio frequency signals received at the antenna to the receiver; and a controllable circuit path coupled to the diode, the circuit path to selectively provide a forward bias current to the diode, the circuit path to change a state of the antenna to transmit data via modulating backscatter by the antenna. - View Dependent Claims (16, 17, 18, 19)
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20. A method implemented in a radio frequency identification system, the method comprising:
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applying a first voltage to a control point of an electronic current path to forward bias a diode coupled between an antenna and a receiver, wherein when forward biased an impedance of the diode for signals propagating from the antenna to the receiver is reduced; and applying a voltage to the control point according to a data to be transmitted via the antenna to change an impedance of the current path to modulate backscattering of electromagnetic wave backscattered by the antenna. - View Dependent Claims (21)
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Specification