Micro-electromechanical systems
First Claim
1. A micro-electromechanical system (MEMS) comprising:
- a substrate incorporating an oscillatory member;
forcing means for driving the oscillatory member into resonance;
electrical sensing means for providing an electrical output signal dependent on oscillation of the oscillatory member as a result of such forcing and any externally applied force, anda positive feedback circuit dependent on the output signal of the sensing means for feeding back a signal to the forcing means in order to sustain oscillation of the oscillatory member, wherein the forcing means comprises n (where n is an integer and n≧
2) forcers for applying forces of substantially equal magnitude to the oscillatory member at points which are distributed at angular intervals of 2π
/n radians around the oscillatory member to preferentially stimulate a flexural mode.
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Abstract
A micro-electromechanical system (MEMS) comprises a substrate incorporating an oscillatory ring, forcing electrodes for driving the ring into resonance, and sensing electrodes providing an electrical output signal dependent on oscillation of the ring as a result of such forcing and any externally applied force. A positive feedback circuit is provided for feeding back a signal dependent on the output signal of the sensing electrodes to the forcing electrodes in order to sustain oscillation of the ring. The use of positive feedback to drive the forcing electrodes in order to sustain oscillation of the ring is highly advantageous in such an application since it produces a system which exhibits very low phase noise of a magnitude considerably less than the phase noise experienced in use of a phase-lock loop circuit to sustain oscillation.
44 Citations
23 Claims
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1. A micro-electromechanical system (MEMS) comprising:
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a substrate incorporating an oscillatory member; forcing means for driving the oscillatory member into resonance; electrical sensing means for providing an electrical output signal dependent on oscillation of the oscillatory member as a result of such forcing and any externally applied force, and a positive feedback circuit dependent on the output signal of the sensing means for feeding back a signal to the forcing means in order to sustain oscillation of the oscillatory member, wherein the forcing means comprises n (where n is an integer and n≧
2) forcers for applying forces of substantially equal magnitude to the oscillatory member at points which are distributed at angular intervals of 2π
/n radians around the oscillatory member to preferentially stimulate a flexural mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 20, 21, 22, 23)
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17. A micro-electromechanical system (MEMS), said system comprising:
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a substrate incorporating an oscillatory member, forcing means for driving the oscillatory member into resonance, and electrical sensing means providing an electrical output signal dependent on oscillation of the oscillatory member as a result of such forcing and any externally applied force, wherein the forcing means comprises n (where n is an integer and n≧
2) forcers for applying substantially equal forces to the oscillatory member at points which distributed at angular intervals of 2π
/n radians around the oscillatory member. - View Dependent Claims (18, 19)
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Specification