Force rebalancing for MEMS inertial sensors using time-varying voltages
First Claim
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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; and
a plurality of torquer electrodes positioned adjacent to each of the one or more proof masses, wherein the torquer electrodes comprise;
one or more first torquer electrodes adapted to selectively control Coriolis-related motion of the one or more proof masses along the sense axis; and
one or more second torquer electrodes adapted to selectively control quadrature-related motion of the one or more proof masses along the sense axis; and
one or more time-varying rebalancing voltages applied to said torquer electrodes, the rebalancing voltages adapted to maintain a fixed capacitance between each sense electrode and its corresponding proof mass.
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Abstract
MEMS devices and methods employing one or more electrodes coupled to a time-varying rebalancing voltage are disclosed. A MEMS inertial sensor in accordance with an illustrative embodiment can include one or more proof masses, at least one sense electrode positioned adjacent to each proof mass, and one or more torquer electrodes. Rebalancing voltages can be applied to the torquer electrodes to electrostatically null quadrature and/or Coriolis-related proof mass motion along a sense axis of the device. The rebalancing voltages applied to each of the torquer electrodes can be adjusted using feedback from one or more force rebalancing control loops.
105 Citations
27 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; and a plurality of torquer electrodes positioned adjacent to each of the one or more proof masses, wherein the torquer electrodes comprise; one or more first torquer electrodes adapted to selectively control Coriolis-related motion of the one or more proof masses along the sense axis; and one or more second torquer electrodes adapted to selectively control quadrature-related motion of the one or more proof masses along the sense axis; and one or more time-varying rebalancing voltages applied to said torquer electrodes, the rebalancing voltages adapted to maintain a fixed capacitance between each sense electrode and its corresponding proof mass. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. 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 capacitively sense proof mass motion along a sense axis perpendicular to a drive axis of the one or more proof masses; a first number of torquer electrodes adapted to provide rebalancing forces on said proof masses along the sense axis in a first direction, the first number of torquer electrodes adapted to selectively control Coriolis-related motion of the one or more proof masses along the sense axis; and a second number of torquer electrodes adapted to provide rebalancing forces in an opposite direction from the first direction along the sense axis, the second number of torquer electrodes adapted to selectively control quadrature-related motion of the one or more proof masses along the sense axis; wherein the rebalancing forces are adapted to maintain a fixed capacitance between each sense electrode and corresponding proof mass based on feedback from one or more force rebalancing control loops. - View Dependent Claims (26)
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19. A method of force rebalancing a MEMS inertial sensor, the MEMS inertial sensor including one or more proof masses adapted to oscillate at a motor drive frequency, and at least one sense electrode positioned adjacent to each of the one or more proof masses, each sense electrode coupled to a sense bias voltage source for sensing displacement of the one or more proof masses along a sense axis perpendicular to a drive axis of the one or more proof masses, the method comprising the steps of:
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applying one or more time-varying rebalancing voltages to a plurality of torquer electrodes adjacent to each proof mass, wherein applying the rebalancing voltages comprises; providing a first rebalancing voltage to a first number of torquer electrodes adapted to selectively control Coriolis-related motion of the one or more proof masses along the sense axis; and providing a second rebalancing voltage to a second number of torquer electrodes adapted to selectively control quadrature-related motion of the one or more proof masses along the sense axis; sensing any displacement of the one or more proof masses along the sense axis and outputting a sense voltage having an amplitude in proportion to the proof mass displacement; and electrostatically nulling any proof mass motion along the sense axis based on the outputted sense voltage. - View Dependent Claims (20, 21, 22, 23, 24, 25, 27)
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Specification