Passive wireless sensor
First Claim
1. A passive wireless transponder, comprising:
- an antenna,a rectifier to convert a RF power of a received radio frequency (RF) interrogating signal into a direct current (DC),a tag oscillator configured to generate a modulation frequency and an internal clock, a demodulator adapted to demodulate a received RFID interrogating command from the received RF interrogating signal, a digital control part that uses the internal clock and is adapted to process the received RFID interrogating command and to output a digital response,a modulator adapted to generate a modulated backscattered signal carrying the digital response for communication with a backscattering principle to provide radio frequency identification (RFID) features, anda sensing element for sensing a predetermined variable,wherein the modulated backscattered signal carrying a digital response comprises sidebands that are offset from an interrogation frequency by a modulation frequency outputted from the tag oscillator, and wherein the tag oscillator is based on a resonator, and the sensing element is connected to the tag oscillator to load the tag oscillator, and the modulation frequency outputted from the tag oscillator and thereby the offset of the sidebands of the modulated backscattered signal are arranged to be dependent on and carry a sensed value of the predetermined variable.
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Accused Products
Abstract
The RFID sensor tag may include normal RFID circuits and functions (such as rectifier, modulator, logic and memory) as well as a resonator-based clock generator or oscillator. The oscillator is a stable resonator-based oscillator having a high Q value. The resonator-based oscillator is loaded with a sensor element which tunes the oscillation frequency, i.e. the oscillation frequency is sensitive to the measured quantity. Thereby, a passive RFID sensor with a resonator-based oscillator and a sensor element is provided, wherein the oscillation frequency can be made dependent on the sensor element if sensing is required. The concept is compatible for existing RFID tags and can enable the possibility to measure external quantities with-out reducing the read-out distance.
24 Citations
16 Claims
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1. A passive wireless transponder, comprising:
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an antenna, a rectifier to convert a RF power of a received radio frequency (RF) interrogating signal into a direct current (DC), a tag oscillator configured to generate a modulation frequency and an internal clock, a demodulator adapted to demodulate a received RFID interrogating command from the received RF interrogating signal, a digital control part that uses the internal clock and is adapted to process the received RFID interrogating command and to output a digital response, a modulator adapted to generate a modulated backscattered signal carrying the digital response for communication with a backscattering principle to provide radio frequency identification (RFID) features, and a sensing element for sensing a predetermined variable, wherein the modulated backscattered signal carrying a digital response comprises sidebands that are offset from an interrogation frequency by a modulation frequency outputted from the tag oscillator, and wherein the tag oscillator is based on a resonator, and the sensing element is connected to the tag oscillator to load the tag oscillator, and the modulation frequency outputted from the tag oscillator and thereby the offset of the sidebands of the modulated backscattered signal are arranged to be dependent on and carry a sensed value of the predetermined variable. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A system comprising
an RFID reader, and at least one passive wireless transponder that further comprises: -
an antenna, a rectifier to convert a RF power of a received radio frequency (RF) interrogating signal into a direct current (DC), a tag oscillator configured to generate a modulation frequency and an internal clock, a demodulator adapted to demodulate a received RFID interrogating command from the received RF interrogating signal, a digital control part that uses the internal clock and is adapted to process the received RFID interrogating command and to output a digital response, a modulator adapted to generate a modulated backscattered signal carrying the digital response for communication with a backscattering principle to provide radio frequency identification (RFID) features, and a sensing element for sensing a predetermined variable, wherein the modulated backscattered signal carrying a digital response comprises sidebands that are offset from an interrogation frequency by a modulation frequency outputted from the tag oscillator, and wherein the tag oscillator is based on a resonator, and the sensing element is connected to the tag oscillator to load the tag oscillator, and the modulation frequency outputted from the tag oscillator and thereby the offset of the sidebands of the modulated backscattered signal are arranged to be dependent on and carry a sensed value of the predetermined variable.
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Specification