FORCE FEEDBACK ELECTRODES IN MEMS ACCELEROMETER
First Claim
1. A method, comprising:
- detecting, by at least one sense capacitor within an apparatus, an acceleration of a proof mass within the apparatus;
applying a feedback force to the proof mass via at least one feedback capacitor, wherein the feedback force is based on the acceleration of the proof mass; and
determining an acceleration of the apparatus based on the feedback force.
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Abstract
A microelectromechanical system (MEMS) accelerometer having separate sense and force-feedback electrodes is disclosed. The use of separate electrodes may in some embodiments increase the dynamic range of such devices. Other possible advantages include, for example, better sensitivity, better noise suppression, and better signal-to-noise ratio. In one embodiment, the accelerometer includes three silicon wafers, fabricated with sensing electrodes forming capacitors in a fully differential capacitive architecture, and with separate force feedback electrodes forming capacitors for force feedback. These electrodes may be isolated on a layer of silicon dioxide. In some embodiments, the accelerometer also includes silicon dioxide layers, piezoelectric structures, getter layers, bonding pads, bonding spacers, and force feedback electrodes, which may apply a restoring force to the proof mass region. MEMS accelerometers with force-feedback electrodes may be used in geophysical surveys, e.g., for seismic sensing or acoustic positioning.
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Citations
20 Claims
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1. A method, comprising:
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detecting, by at least one sense capacitor within an apparatus, an acceleration of a proof mass within the apparatus; applying a feedback force to the proof mass via at least one feedback capacitor, wherein the feedback force is based on the acceleration of the proof mass; and determining an acceleration of the apparatus based on the feedback force. - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus, comprising:
a MEMS accelerometer configured to measure Z-axis acceleration, wherein the MEMS accelerometer includes; a sense electrode configured to detect changes in position of a proof mass in the MEMS accelerometer; and a force feedback electrode configured to provide a restoring force to the proof mass, wherein the restoring force is based on the detected changes in the position of the proof mass. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus, comprising:
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a central substrate region; a first bonded substrate opposing a first surface of the central substrate region; a second bonded substrate opposing a second surface of the central substrate region; a first sense capacitor and a first force feedback capacitor formed between the first bonded substrate and the central substrate region; and a second sense capacitor and a second force feedback capacitor formed between the second bonded substrate and the central substrate region. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification