Micromachined sensor with quadrature suppression

• US 20050139005A1
• Filed: 02/25/2005
• Published: 06/30/2005
• Est. Priority Date: 02/06/2002
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Geen, John A.
• Granted Patent: US 7,032,451 B2
• Time in Patent Office: Days
• US Class Current: 73/504.140
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: Y10T 74/12 Gyroscopes

Abstract

Quadrature suppression is provided by placing a resonator mass adjacent to a quadrature suppression electrode. The resonator mass is capable of moving substantially parallel to the quadrature suppression electrode and includes a notch formed adjacent to a portion of the quadrature suppression electrode such that a length of resonator mass that is directly adjacent to the quadrature suppression electrode varies as the resonator mass moves relative to the quadrature suppression electrode. The quadrature suppression electrode is capable of producing a lateral force on the resonator mass that varies based on the length of resonator mass that is directly adjacent to the quadrature suppression electrode. Such quadrature suppression can be used in sensors having one or more resonator masses.

Claims

1. A micromachined sensor with quadrature suppression comprising:

a quadrature suppression electrode; and

a resonator mass positioned adjacent to the quadrature suppression electrode, the resonator mass capable of moving substantially parallel to the quadrature suppression electrode, the resonator mass including a notch formed adjacent to a portion of the quadrature suppression electrode such that a length of resonator mass that is directly adjacent to the quadrature suppression electrode varies as the resonator mass moves relative to the quadrature suppression electrode, wherein the quadrature suppression electrode is capable of producing a lateral force on the resonator mass that varies based on the length of resonator mass that is directly adjacent to the quadrature suppression electrode.

2. A micromachined sensor according to claim 1, wherein the lateral force is an electrostatic force.

3. A micromachined sensor according to claim 1, further comprising a constant voltage applied to the quadrature suppression electrode, wherein the lateral force is proportional to the length of resonator mass that is directly adjacent to the quadrature suppression electrode.

4. A micromachined sensor according to claim 1, further comprising a varying voltage applied to the quadrature suppression electrode, wherein the lateral force varies as a function of the length of resonator mass that is directly adjacent to the quadrature suppression electrode and the varying voltage.

5. A micromachined sensor according to claim 1, further comprising:

at least one drive electrode for causing movement of the resonator mass substantially parallel to the quadrature suppression electrode.

7. A micromachined sensor according to claim 1, further comprising a voltage applied to at least one of the plurality of quadrature suppression electrodes determined to reduce quadrature of the resonator masses.

8. A micromachined sensor according to claim 1, wherein the resonator masses are mechanically coupled through a plurality of levers, pivots, and flexures so as to produce substantially a single resonance frequency for the plurality of resonator masses.

9. A micromachined sensor according to claim 8, wherein the plurality of resonator masses includes:

a first pair of masses mechanically coupled through a flexure; and

a second pair of masses mechanically coupled through a flexure, wherein the first pair of masses and the second pair of masses resonate in anti-phase to one another.

10. A micromachined sensor according to claim 1, wherein a plurality of resonator masses are electrically coupled through common drive and velocity sensing circuits such as to resonate at substantially a single frequency.

6. A micromachined sensor with quadrature suppression comprising:

a plurality of quadrature suppression electrodes; and

a plurality of resonator masses, each resonator mass positioned adjacent to a respective one of the quadrature suppression electrodes and capable of moving substantially parallel to its respective quadrature suppression electrode, each resonator mass including a notch formed adjacent to a portion of its respective quadrature suppression electrode such that a length of resonator mass that is directly adjacent to the quadrature suppression electrode varies as the resonator mass moves relative to the quadrature suppression electrode, wherein each quadrature suppression electrode is capable of producing a lateral force on its respective resonator mass that varies based on the length of resonator mass that is directly adjacent to the quadrature suppression electrode.

11. A micromachined sensor with quadrature suppression comprising:

a substrate;

a frame suspended above and substantially parallel to the substrate by a first plurality of suspension flexures disposed along an outer perimeter of the frame, the first plurality of suspension flexures affixed to the substrate and formed so as to substantially prevent translational movement of the frame relative to the substrate within a plane of the frame and to permit rotational movement of the frame about an axis perpendicular to the frame and the substrate;

a plurality of quadrature suppression electrodes; and

a plurality of resonator structures disposed within an inner perimeter of the frame, the resonator structures operating substantially within the plane of the frame, the resonator structures including a plurality of resonator masses, each resonator mass positioned adjacent to a respective one of the quadrature suppression electrodes and capable of moving substantially parallel to its respective quadrature suppression electrode, each resonator mass including a notch formed adjacent to a portion of its respective quadrature suppression electrode such that a length of resonator mass that is directly adjacent to the quadrature suppression electrode varies as the resonator mass moves relative to the quadrature suppression electrode, wherein each quadrature suppression electrode is capable of producing a lateral force on its respective resonator mass that varies based on the length of resonator mass that is directly adjacent to the quadrature suppression electrode.

12. A micromachined sensor according to claim 11, wherein the plurality of resonator structures is suspended solely from the inner perimeter of the frame.

13. A micromachined sensor according to claim 11, wherein the resonator masses are mechanically coupled through a plurality of levers, pivots, and flexures so as to produce substantially a single resonance frequency for the plurality of resonator masses.

14. A micromachined sensor according to claim 13, wherein the plurality of resonator masses includes:

a first pair of masses mechanically coupled through a flexure; and

a second pair of masses mechanically coupled through a flexure, wherein the first pair of masses and the second pair of masses resonate in anti-phase to one another.

15. A micromachined sensor according to claim 13, wherein each of the levers includes a plurality of lever fingers interdigitated with corresponding fingers affixed to the substrate for at least one of driving the lever and sensing position of the lever.

16. A micromachined sensor according to claim 15, wherein each of the levers moves with an arcuate motion, and wherein the lever fingers are disposed at varying angles so as to maintain substantially equal distances from said corresponding fixed fingers during movement of the levers.

17. A micromachined sensor according to claim 11, further comprising:

a plurality of frame fingers disposed along the outer perimeter of the frame, the frame fingers interdigitated with corresponding sensing fingers affixed to the substrate for sensing said rotational movement of the frame.

18. A micromachined sensor according to claim 17, wherein the frame fingers are disposed at varying angles so as to maintain substantially equal distances from said corresponding sensing fingers during rotational movement of the frame.

19. A micromachined sensor according to claim 11, wherein each resonator mass includes a plurality of drive fingers interdigitated with a corresponding array of fixed drive fingers affixed to the substrate.

20. A micromachined sensor according to claim 19, wherein each array of fixed drive fingers is affixed to the substrate using a plurality of anchors, and wherein the anchors for pairs of anti-phase arrays of fixed drive fingers are arranged to be co-linear in a lateral direction relative to the motion of the mass.

21. A micromachined sensor according to claim 11, wherein the outer perimeter of the frame is substantially square and includes a plurality of frame fingers disposed along each side of the frame, the frame fingers interdigitated with corresponding sensing fingers affixed to the substrate for sensing said rotational movement of the frame that is induced by Coriolis acceleration when the resonator structures are resonating and the apparatus is rotated about the axis.

22. A micromachined sensor according to claim 11, wherein a plurality of resonator masses are electrically coupled through common drive and velocity sensing circuits such as to resonate at substantially a single frequency.