Transponder with stabilized oscillator
First Claim
Patent Images
1. A transponder, comprising:
- a rectifier;
an oscillator configured for squegging to stop oscillations before the oscillator reaches steady state operation;
a hysteretic switch coupled between the rectifier and the oscillator, wherein the hysteretic switch is operative to selectively switch scavenged power to the oscillator, and a turn-on transient period exists after power is applied to the oscillator; and
a radiative structure coupled both to the rectifier and the oscillator.
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Abstract
A coherent RFID tag design having no internal power source is disclosed. The design exhibits a longer detection range and less interference relative to conventional tag designs. The coherent RFID tag design operates in a locked or stabilized fashion, in that the frequency at which energy is parasitically coupled to the RFID tag (via its antenna) is the same as the frequency at which the RFID tag transmits information utilizing the same antenna. The RFID tag design allows a greater number of RFID tags to be deployed, without causing cross-tag interference issues and the like.
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Citations
21 Claims
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1. A transponder, comprising:
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a rectifier; an oscillator configured for squegging to stop oscillations before the oscillator reaches steady state operation; a hysteretic switch coupled between the rectifier and the oscillator, wherein the hysteretic switch is operative to selectively switch scavenged power to the oscillator, and a turn-on transient period exists after power is applied to the oscillator; and a radiative structure coupled both to the rectifier and the oscillator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A transponder, comprising:
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a rectifier; an oscillator configured for squegging to stop oscillations before the oscillator reaches its steady state operation; a hysteretic switch coupled between the rectifier and the oscillator, the hysteretic switch operative to switch a capacitor to the oscillator when voltage across the capacitor is above a first threshold voltage, and to maintain connection of the capacitor to the oscillator until charge on the capacitor drops below a second threshold voltage that is lower than the first threshold voltage, wherein once the first threshold voltage is reached on the capacitor, the hysteretic switch begins to conduct and there is a turn-on transient period which exists after power from the capacitor is applied, but before steady state of the oscillator is reached; and a radiative structure coupled both to the rectifier and the oscillator; wherein during the turn-on transient period, oscillations output by the oscillator increase in amplitude and are coherent with an external input signal. - View Dependent Claims (14, 15)
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16. A system, comprising:
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a plurality of transponders, each transponder comprising; a rectifier; an oscillator configured for squegging to stop oscillations before the oscillator reaches steady state operation, wherein the oscillator has an output that is coherent with an external input signal; a hysteretic switch coupled between the rectifier and the oscillator, wherein the hysteretic switch is operative to selectively switch a scavenged power to the oscillator, and a turn-on transient period exists after power is applied to the oscillator; and a radiative structure coupled both to the rectifier and the oscillator; wherein the plurality of transponders emit coherent signals in phase with one another and act as elements of a spatial antenna array. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification