Ferroelectric varactors suitable for capacitive shunt switching and wireless sensing
First Claim
1. A passive sensor, the passive sensor comprising:
- a varactor shunt switch, wherein said varactor shunt switch comprises;
a substrate;
a patterned bottom metal layer deposited on said substrate;
a ferroelectric thin film is deposited on said patterned bottom metal layer; and
a top metal electrode deposited on said ferroelectric thin film, wherein said top metal electrode is patterned to form a coplanar waveguide transmission line and wherein the surface potential of said top metal electrode changes in the presence of a form of directed energy, wherein the capacitance of said varactor shunt switch will change in response to changes of said surface potential.
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Abstract
A ferroelectric varactor suitable for capacitive shunt switching is disclosed. High resistivity silicon with a SiO2 layer and a patterned metallic layer deposited on top is used as the substrate. A ferroelectric thin-film layer deposited on the substrate is used for the implementation of the varactor. A top metal electrode is deposited on the ferroelectric thin-film layer forming a CPW transmission line. By using the capacitance formed by the large area ground conductors in the top metal electrode and bottom metallic layer, a series connection of the ferroelectric varactor with the large capacitor defined by the ground conductors is created. The large capacitor acts as a short to ground, eliminating the need for vias. In one embodiment, the varactor shunt switch can be used as passive sensor with the capability of being wireless.
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Citations
36 Claims
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1. A passive sensor, the passive sensor comprising:
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a varactor shunt switch, wherein said varactor shunt switch comprises;
a substrate;
a patterned bottom metal layer deposited on said substrate;
a ferroelectric thin film is deposited on said patterned bottom metal layer; and
a top metal electrode deposited on said ferroelectric thin film, wherein said top metal electrode is patterned to form a coplanar waveguide transmission line and wherein the surface potential of said top metal electrode changes in the presence of a form of directed energy, wherein the capacitance of said varactor shunt switch will change in response to changes of said surface potential. - View Dependent Claims (2, 3, 4, 5)
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6. A passive sensor, the passive sensor comprising:
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a varactor shunt switch, wherein said varactor shunt switch comprises;
a substrate;
a patterned bottom metal layer deposited on said substrate;
a functionalized polymer thin film is spin coated on said patterned bottom metal layer; and
a top metal electrode deposited on said functionalized polymer thin film, wherein said top metal electrode is patterned to form a coplanar waveguide transmission line and wherein the surface potential of said top metal electrode changes in the presence of a chemical or biochemical agent due to a chemical reaction with said functionalized polymer thin film, wherein the capacitance of said varactor shunt switch will change in response to changes of said surface potential. - View Dependent Claims (7, 8, 9)
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10. A passive piezoelectric sensor, the passive piezoelectric sensor comprising:
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a varactor shunt switch, wherein said varactor shunt switch comprises;
a substrate;
a patterned bottom metal layer deposited on said substrate;
a ferroelectric thin film is deposited on said patterned bottom metal layer; and
a top metal electrode deposited on said ferroelectric thin film, wherein said top metal electrode is patterned to form a coplanar waveguide transmission line. wherein said varactor shunt switch is responsive to changes in pressure or force due to the piezoelectric property of said ferroelectric thin film. - View Dependent Claims (11)
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12. A passive sensor, the passive sensor comprising:
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a varactor shunt switch, wherein said varactor shunt switch comprises;
a substrate;
a patterned bottom metal layer deposited on said substrate;
a thin film is deposited on said patterned bottom metal layer; and
a top metal electrode deposited on said thin film, wherein said top metal electrode is patterned to form a coplanar waveguide transmission line, wherein the capacitance of said varactor shunt switch will change in response to changes of surface potential of said top metal electrode; and
an antenna integrated with said varactor shunt switch, wherein said antenna is responsive to a radio frequency signal sent by a radar. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A method of passive sensing, the method comprising:
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depositing an adhesion layer on a substrate;
depositing a pattern bottom metal layer on said adhesion layer;
covering said pattern bottom metal layer with a layer of thin film, wherein said pattern bottom metal layer comprises of at least two ground conductors and a shunt conductor;
topping said layer of thin film with a top metal electrode, wherein said top metal electrode comprises of at least two ground conductors and a center signal strip; and
sensing changes in capacitance due to changes in surface potential of said top metal electrode. - View Dependent Claims (20, 21, 22, 23, 24, 25)
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26. A method of passive wireless sensing, the method comprising:
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depositing an adhesion layer on a substrate;
depositing a pattern bottom metal layer on said adhesion layer;
covering said pattern bottom metal layer with a layer of thin film, wherein said pattern bottom metal layer comprises of at least two ground conductors and a shunt conductor;
topping said layer of thin film with a top metal electrode, wherein said top metal electrode comprises of at least two ground conductors and a center signal strip; and
integrating an antenna, wherein said antenna is responsive to a radio frequency signal sent by a radar. - View Dependent Claims (27, 28, 29)
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30. A passive sensor, the passive sensor comprising:
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a varactor shunt switch, wherein said varactor shunt switch comprises;
a substrate;
a patterned bottom metal layer deposited on said substrate;
a ferroelectric thin film is deposited on said patterned bottom metal layer; and
a top metal electrode deposited on said ferroelectric thin film, wherein said top metal electrode is patterned to form a coplanar waveguide transmission line;
wherein changes in capacitance of said varactor shunt switch resulting from external stimuli are monitored. - View Dependent Claims (31)
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32. A passive sensor, the passive sensor comprising:
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a varactor shunt switch, wherein said varactor shunt switch comprises;
a substrate;
a patterned bottom metal layer deposited on said substrate;
a ferroelectric thin film deposited on said patterned bottom metal layer; and
a top metal electrode deposited on said ferroelectric thin film, wherein said top metal electrode is patterned to form a coplanar waveguide transmission line. wherein the output of said varactor shunt switch is responsive to changes in capacitance and wherein said changes in capacitance and output are monitored.
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33. A passive sensor, the passive sensor comprising:
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a varactor shunt switch, wherein said varactor shunt switch comprises;
a substrate;
a patterned bottom metal layer deposited on said substrate;
a thin film is deposited on said patterned bottom metal layer; and
a top metal electrode deposited on said thin film, wherein said top metal electrode is patterned to form a coplanar waveguide transmission line, wherein the capacitance of said varactor shunt switch will change in response to changes of surface potential of said top metal electrode due to external stimuli and wherein the output of said varactor shunt switch will change in response to the changes of capacitance.
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34. A method of passive sensing, the method comprising:
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depositing an adhesion layer on a substrate;
depositing a pattern bottom metal layer on said adhesion layer;
covering said pattern bottom metal layer with a layer of thin film, wherein said pattern bottom metal layer comprises of at least two ground conductors and a shunt conductor;
topping said layer of thin film with a top metal electrode, wherein said top metal electrode comprises of at least two ground conductors and a center signal strip; and
sensing changes in capacitance due to changes in surface potential of said top metal electrode resulting from external stimuli. - View Dependent Claims (35)
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36. A method of passive sensing, the method comprising:
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depositing an adhesion layer on a substrate;
depositing a pattern bottom metal layer on said adhesion layer;
covering said pattern bottom metal layer with a layer of thin film, wherein said pattern bottom metal layer comprises of at least two ground conductors and a shunt conductor;
topping said layer of thin film with a top metal electrode, wherein said top metal electrode comprises of at least two ground conductors and a center signal strip;
sensing changes in capacitance due to changes in surface potential of said top metal electrode resulting from external stimuli; and
monitoring changes in output due to the changes in capacitance.
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Specification