Monolithic accelerometer
First Claim
1. A monolithic semiconductor capacitance-type accelerometer comprising;
- a semiconductor substrate comprising a surface,a plurality of posts extending from the surface of said substrate,a polysilicon bridge suspended from said posts, said bridge comprising a plurality of moveable fingers,a plurality of electrically conductive substantially stationary fingers, each of said substantially stationary fingers corresponding to one of said moveable fingers and positioned relative to said corresponding moveable finger such that said moveable finger and said corresponding substantially stationary finger form a capacitor,whereby movement of said bridge under an accelerative force causes said moveable fingers to move relative to said substantially stationary fingers and alter the capacitance between said moveable fingers and said corresponding stationary fingers, andcircuitry disposed on said substrate and coupled to said moveable fingers and said substantially stationary fingers for generating a signal indicative of acceleration.
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Accused Products
Abstract
An accelerometer comprising a microfabricated acceleration sensor and monolithically fabricated signal conditioning circuitry. The sensor comprises a differential capacitor arrangement formed by a pair of capacitors. Each capacitor has two electrodes, one of which it shares electrically in common with the other capacitor. One of the electrodes (e.g., the common electrode) is movable and one of the electrodes is stationary in response to applied acceleration. The electrodes are all formed of polysilicon members suspended above a silicon substrate. Each of the capacitors is formed of a plurality of pairs of electrode segments electrically connected in parallel and, in the case of the movable electrodes, mechanically connected to move in unison. When the substrate is accelerated, the movable electrodes move such that the capacitance of one of the capacitors increases, while that of the other capacitor decreases. The two capacitors are connected to signal conditioning circuitry which converts this differential capacitance into a corresponding voltage. Both open loop and force-balance operation are shown.
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Citations
26 Claims
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1. A monolithic semiconductor capacitance-type accelerometer comprising;
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a semiconductor substrate comprising a surface, a plurality of posts extending from the surface of said substrate, a polysilicon bridge suspended from said posts, said bridge comprising a plurality of moveable fingers, a plurality of electrically conductive substantially stationary fingers, each of said substantially stationary fingers corresponding to one of said moveable fingers and positioned relative to said corresponding moveable finger such that said moveable finger and said corresponding substantially stationary finger form a capacitor, whereby movement of said bridge under an accelerative force causes said moveable fingers to move relative to said substantially stationary fingers and alter the capacitance between said moveable fingers and said corresponding stationary fingers, and circuitry disposed on said substrate and coupled to said moveable fingers and said substantially stationary fingers for generating a signal indicative of acceleration. - View Dependent Claims (2, 3, 4)
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5. A monolithic semiconductor capacitance-type accelerometer comprising;
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a semiconductor substrate comprising a surface, a plurality of posts extending from the surface of said substrate, a polysilicon bridge suspended from said substrate by said posts, said bridge comprising a central beam and a plurality of generally parallel moveable fingers extending transversely from said beam, a plurality of generally parallel electrically conductive substantially stationary fingers, each of said substantially stationary fingers corresponding to one of said moveable fingers and positioned relative to said corresponding moveable finger such that said moveable finger and corresponding substantially stationary finger form a capacitor, whereby movement of said bridge under an accelerative force causes said moveable fingers to move relative to said substantially stationary fingers and alter the capacitance between each of said moveable fingers and said corresponding substantially stationary finger, and circuitry disposed on said substrate and coupled to said moveable fingers and said substantially stationary fingers for generating a signal indicative of acceleration. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification