Variable capacitor and associated fabrication method
First Claim
1. A microelectromechanical system (MEMS) variable capacitor comprising:
- a substrate;
at least one substrate electrode disposed upon said substrate, said at least one substrate electrode comprising a low electrical resistance material; and
a bimorph member extending outwardly from said substrate and over said at least one substrate electrode, said bimorph member comprising first and second layers formed of materials having different coefficients of thermal expansion, said bimorph member comprising at least one bimorph electrode such that a voltage differential established between said at least one substrate electrode and said at least one bimorph electrode further moves said bimorph member relative to said at least one substrate electrode to thereby alter an interelectrode spacing.
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Accused Products
Abstract
A variable capacitor having low loss and a correspondingly high Q is provided. In addition to a substrate, the variable capacitor includes at least one substrate electrode and a substrate capacitor plate that are disposed upon the substrate and formed of a low electrical resistance material, such as HTS material or a thick metal layer. The variable capacitor also includes a bimorph member extending outwardly from the substrate and over the at least one substrate electrode. The bimorph member includes first and second layers formed of materials having different coefficients of thermal expansion. The first and second layers of the bimorph member define at least one bimorph electrode and a bimorph capacitor plate such that the establishment of a voltage differential between the substrate electrode and the bimorph electrode moves the bimorph member relative to the substrate electrode, thereby altering the interelectrode spacing as well as the distance between the capacitor plates. As such, the capacitance of the variable capacitor can be controlled based upon the relative spacing between the bimorph member and the underlying substrate. A method is also provided for micromachining or otherwise fabricating a variable capacitor having an electrode and a capacitor plate formed of a low electrical resistance material such that the resulting variable capacitor has low loss and a correspondingly high Q. The variable capacitor can therefore be employed in high frequency applications, such as required by some tunable filters.
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Citations
33 Claims
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1. A microelectromechanical system (MEMS) variable capacitor comprising:
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a substrate;
at least one substrate electrode disposed upon said substrate, said at least one substrate electrode comprising a low electrical resistance material; and
a bimorph member extending outwardly from said substrate and over said at least one substrate electrode, said bimorph member comprising first and second layers formed of materials having different coefficients of thermal expansion, said bimorph member comprising at least one bimorph electrode such that a voltage differential established between said at least one substrate electrode and said at least one bimorph electrode further moves said bimorph member relative to said at least one substrate electrode to thereby alter an interelectrode spacing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 32)
an anchor between the bimorph member and the substrate that is configured to mechanically bias the bimorph member to contact the substrate.
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21. A MEMS variable capacitor comprising:
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a substrate;
a substrate capacitor plate disposed upon said substrate, said substrate capacitor plate comprising a low electrical resistance material;
at least one substrate electrode disposed upon said substrate and spaced from said substrate capacitor plate, said at least one substrate electrode comprising a low electrical resistance material;
a bimorph member extending outwardly from said substrate and over said at least one substrate electrode, said bimorph member comprising a bimorph capacitor plate and at least one bimorph electrode; and
at least one dielectric element disposed between substrate electrode and bimorph electrode and disposed between the substrate capacitor plate and the bimorph capacitor plate, wherein a voltage differential established between said at least substrate electrode and said at least one bimorph electrode moves said bimorph member relative to said substrate to thereby alter the spacing between said substrate capacitor plate and said bimorph capacitor plate. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 33)
an anchor between the bimorph member and the substrate that is configured to mechanically bias the bimorph member to contact the substrate.
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Specification