Force rebalancing and parametric amplification of MEMS inertial sensors
First Claim
1. A MEMS inertial sensor, comprising:
- one or more proof masses adapted to oscillate at a motor drive frequency;
at least one sense electrode positioned adjacent to each of the one or more proof masses, the sense electrode adapted to sense proof mass motion along a sense axis perpendicular to a drive axis of the one or more proof masses;
a first number of force rebalancing torquer electrodes coupled to an AC force rebalancing voltage signal and adapted to control Coriolis-related motion of the one or more proof masses; and
a second number of force rebalancing torquer electrodes coupled to a DC force rebalancing voltage signal and adapted to control quadrature-related motion of the one or more proof masses.
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Abstract
MEMS devices and methods for measuring Coriolis forces using force rebalancing and parametric gain amplification techniques are disclosed. A MEMS inertial sensor can include one or more proof masses, at least one sense electrode positioned adjacent to each proof mass, a number of torquer electrodes for electrostatically nulling quadrature and Coriolis-related proof mass motion, and a number of pump electrodes for producing a pumping force on the proof masses. Force rebalancing voltages can be applied to some torquer electrodes to electrostatically null quadrature and/or Coriolis-related proof mass motion along a sense axis of the device. A pumping voltage at approximately twice the motor drive frequency of the proof masses can be used to pump the proof masses along the sense axis.
28 Citations
19 Claims
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1. A MEMS inertial sensor, comprising:
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one or more proof masses adapted to oscillate at a motor drive frequency; at least one sense electrode positioned adjacent to each of the one or more proof masses, the sense electrode adapted to sense proof mass motion along a sense axis perpendicular to a drive axis of the one or more proof masses; a first number of force rebalancing torquer electrodes coupled to an AC force rebalancing voltage signal and adapted to control Coriolis-related motion of the one or more proof masses; and a second number of force rebalancing torquer electrodes coupled to a DC force rebalancing voltage signal and adapted to control quadrature-related motion of the one or more proof masses. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A MEMS inertial sensor, comprising:
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one or more proof masses adapted to oscillate at a motor drive frequency; at least one sense electrode positioned adjacent to each of the one or more proof masses, the sense electrode adapted to sense proof mass motion along a sense axis perpendicular to a drive axis of the one or more proof masses; at least one force rebalancing electrode coupled to a time-varying rebalancing voltage, the time-varying rebalancing voltage having a frequency at half the motor drive frequency; and at least one pump electrode coupled to a pump voltage, the pump voltage having a frequency at twice the motor drive frequency of the one or more proof masses; wherein a pumping force produced by the pump voltage is adapted to parametrically amplify Coriolis forces exerted on the one or more proof masses along the sense axis.
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13. A method of measuring Coriolis forces on a MEMS inertial sensor, comprising the steps of:
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oscillating one or more proof masses at a motor drive frequency; sensing any displacement of the one or more proof masses in a sense mode of oscillation along a sense axis perpendicular to a drive axis of the one or more proof masses; providing a first rebalancing force to the one or more proof masses along the sense axis, the first rebalancing force for controlling a quadrature-related motion of the one or more proof masses; providing a second rebalancing force to the one or more proof masses along the sense axis, the second rebalancing force for controlling a Coriolis-related motion of the one or more proof masses; providing a pumping force to the one or more proof masses along the sense axis at approximately twice the motor drive frequency; and detecting Coriolis forces on the one or more proof masses in the sense mode of oscillation. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification