Micromachined resonant magnetic field sensors
AssigneeInvenSense, Inc.
InventorsJoseph Seeger, Chiung C. Lo, Baris Cagdaser, Derek Shaeffer
Life of this patent
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Abstract
A micromachined magnetic field sensor is disclosed. The micromachined magnetic field sensor includes a substrate; and a drive subsystem partially supported by the substrate with a plurality of beams, and at least one anchor; a mechanism for providing an electrical current through the drive subsystem along a first axis; and Lorentz force acting on the drive subsystem along a second axis in response to a magnetic field vector along a third axis. The micromachined magnetic field sensor also includes a position transducer to detect the motion of the drive subsystem and an electrostatic offset cancellation mechanism coupled to the drive subsystem.
Claims13
A micromachined magnetic field sensor comprising:
- a substrate;
- a drive subsystem with a plurality of beams flexibly coupled to the substrate;
- a mechanism for providing an electrical current through the drive subsystem along a first axis;
- a magnetic field vector along a second axis generates a Lorentz force on the drive subsystem along a third axis;
- a position transducer responds to the Lorentz force on the drive subsystem;
- and
- an offset cancellation mechanism electrostatically coupled to the drive subsystem;
- wherein the offset cancellation mechanism comprises at least one shield structure coupled to the substrate by at least one anchor, wherein the at least one shield structure comprises a plurality of beams spaced equally on opposite sides of the drive subsystem,
- wherein the drive subsystem moves relative to the at least one shield structure.
A micromachined magnetic field sensor comprising:
- a substrate;
- a drive subsystem with a plurality of beams flexibly coupled to the substrate;
- a mechanism for providing an electrical current through the drive subsystem along a first axis;
- a magnetic field along a second axis generates a Lorentz force on the drive subsystem along a third axis;
- a position transducer responds to the Lorentz force acting on the drive subsystem;
- and
- an offset cancellation mechanism electrostatically coupled to the drive subsystem,
- wherein the offset cancellation mechanism comprises force-balanced electrostatic coupling springs comprising two equal coupling capacitors wherein a first electrostatic force generated by a first capacitor is balanced by a second electrostatic force generated by a second capacitor.
A micromachined magnetic field sensor comprising:
- a substrate;
- a drive subsystem with a plurality of beams flexibly coupled to the substrate;
- a mechanism for providing an electrical current through at least one of the plurality of beams of the drive subsystem along a first axis;
- a magnetic field along a second axis generates a Lorentz force on the drive subsystem along a third axis;
- a position transducer responds to the Lorentz force acting on the drive subsystem;
- and
- an offset cancellation mechanism electrostatically coupled to the at least one of the plurality of beams of the drive subsystem,
- wherein the offset cancellation mechanism comprises at least one shield structure coupled to the substrate by at least one anchor, wherein the at least one shield structure is biased with a DC voltage to reduce electrostatic offset forces acting on the at least one beam.
Dependencies are inferred from the claim text.