Tuneable microelectromechanical system resonator
AssigneeNational Semiconductor Corporation
InventorRobert J. Strain
Life of this patent
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Abstract
A resonant beam or cantilever is implemented in single crystal silicon or polysilicon. Adjacent the end of the cantilever is an electrode capable of receiving a variable voltage. The cantilever has a natural mechanical resonant frequency when vibrated, and the varying electrostatic field resulting from the variation of applied voltage to the electrode is used to alter the natural restoring force of the cantilever so that a chosen vibration frequency of the cantilever can be achieved. Such vibrating cantilever can be used as the bases for a voltage control oscillator.
Claims13
A vibratory structure comprising:
- a substrate portion;
- a flexible cantilever connected to the substrate portion, at least a portion of the cantilever capable of carrying an electrical charge of a first polarity, the cantilever having an inherent rest position relative to the substrate portion, and, when deflected from such rest position to a deflected position relative to the substrate portion, having an inherent mechanical restoring force which varies with a displacement between said deflected position and said rest position;
- an electrode adjacent the cantilever for generating an electric charge of a second polarity in accordance with an input voltage to said electrode so that an electric field may be generated by the electrical charge of said first polarity and said electrical charge of said second polarity, for applying a force to the so-charged cantilever portion with the cantilever in said deflected position so that the net restoring force on the cantilever is different from the inherent mechanical restoring force of the cantilever;
- and
- a piezoelectric sensor sensing said displacement for providing said input voltage, said input voltage varying with said displacement.
A vibratory structure comprising:
- a substrate portion;
- a flexible cantilever connected to the substrate portion, at least a portion of the cantilever capable of carrying an electrical charge of a first polarity, the cantilever having an inherent rest position relative to the substrate portion, and, when deflected from such rest position to a deflected position relative to the substrate portion, having an inherent mechanical restoring force;
- a first electrode adjacent the cantilever for generating an electric charge of a second polarity so that an electric field may be generated by the electrical charge of the first polarity and the electrical charge of the second polarity, for applying a force to the so-charged cantilever portion with the cantilever in said deflected position so that the net restoring force on the cantilever is different from the inherent mechanical restoring force of the cantilever;
- and
- a second electrode mounted adjacent the first-mentioned electrode for generating an electric field of said second polarity for applying electrostatic force to the cantilever portion with the cantilever in said rest position relative to the substrate portion to move the cantilever from said rest position.
Dependencies are inferred from the claim text.