Microelectromechanical gyroscopes and related apparatus and methods

• US 8,833,161 B2
• Filed: 04/20/2011
• Issued: 09/16/2014
• Est. Priority Date: 04/20/2010
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Sand 9, Inc. (Analog Devices, Inc.)
• Inventors: Zolfagharkhani, Guiti, Kuypers, Jan H., Gaidarzhy, Alexei, Sparks, Andrew
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US13/091,018
• Publication Number:
  US 20120006113A1
• Time in Patent Office: 1,245 Days
• Field of Search: 735/041.2, 735/041.3
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure
• CPC Class Codes: G01C 19/5755 the devices having a single sensing mass
• CPC Class Codes: H10N 30/40 with electrical input and electrical output, e.g. functioning as transformers
• CPC Class Codes: H10N 30/706 characterised by the underlying bases, e.g. substrates
• CPC Class Codes: H10N 30/87 Electrodes or interconnections, e.g. leads or terminals
• CPC Class Codes: H10N 30/88 Mounts; Supports; Enclosures; Casings

Abstract

In one embodiment, an apparatus includes a resonant structure having a plate, a drive electrode and a sense electrode. The resonant structure defines an axis substantially orthogonal to a plane defined by the plate when the resonant structure is not excited. The plate is formed from a piezoelectric material. The drive electrode is configured to excite the resonant structure, and the sense electrode is configured to sense a signal in response to rotation of the resonant structure about the axis.

Claims

1. An apparatus, comprising:

a resonant structure having a plate, a drive electrode and a sense electrode, a temperature compensated stack, and a substrate,

the resonant structure defining an axis substantially orthogonal to a plane defined by the plate when the resonant structure is not excited, the plate formed from a piezoelectric material,

the drive electrode for applying a voltage to the resonant structure to excite the resonant structure,

the sense electrode for supplying a signal generated by the resonant structure in response to rotation of the resonant structure about the axis;

the temperature compensated stack located between the plate and the substrate; and

the resonant structure being suspended and coupled to the substrate by a plurality of anchors.

2. The apparatus of claim 1, wherein the voltage excites the resonant structure in a first mode, the resonant structure configured to oscillate in a second mode upon rotation about the axis.

3. The apparatus of claim 2, wherein the first mode and the second mode each is an elliptical mode or a flexural mode.

4. The apparatus of claim 2, wherein the first mode and the second mode each is spatially rotated with respect to each other.

5. The apparatus of claim 4, wherein the first mode and the second mode each is rotated relative to each other by approximately 45 degrees.

6. The apparatus of claim 2, wherein the voltage excites the resonant structure in the first mode at a first frequency corresponding to a first resonance frequency of the first mode, a second frequency corresponding to a second resonance frequency of the second mode, or a third frequency different from the first resonance frequency of the first mode and the second resonance frequency of the second mode.

7. The apparatus of claim 1, wherein the plate includes at least one of a disk, a ring, a proof mass or a double mass plate.

8. The apparatus of claim 1, wherein at least one anchor from the plurality of anchors is a multi-element anchor.

9. The apparatus of claim 1, wherein the piezoelectric material is at least one of Aluminum nitride, Zinc oxide, or PZT.

10. The apparatus of claim 1, wherein the resonant structure includes at least one of silicon or a piezoelectric thin film.

11. The apparatus of claim 1, wherein the voltage drives the resonant structure differentially.

12. The apparatus of claim 1, wherein a second electrode is used for detecting the resonant structure differentially.

13. The apparatus of claim 1, wherein the resonant structure comprises a crystalline material having a crystal orientation, and wherein the resonant structure is rotated with respect to a crystalline direction.

14. The apparatus of claim 1, wherein the resonant structure comprises a crystalline material having a crystal orientation, and wherein at least one of the drive electrode, the sense electrode, and the resonating structure is rotated with respect to a crystalline direction of materials.

15. The apparatus of claim 1, further comprising:

a microelectromechanical system (MEMS) accelerometer, a MEMS accelerometer and the resonant structure being integrated on a common chip.

16. The apparatus of claim 1, further comprising:

a microelectromechanical system (MEMS) timing oscillator, a MEMS accelerometer and the resonant structure being integrated on a common chip.

17. The apparatus of claim 1, wherein the resonant structure is a first resonant structure, the apparatus further comprising:

a second resonant structure having a second plate, a second drive electrode and a second sense electrode, the second resonant structure defining a second axis substantially orthogonal to a second plane defined by the second plate of the second resonant structure when the second resonant structure is not excited, the second plate of the second resonant structure formed from a second piezoelectric material, the second drive electrode of the second resonant structure used for applying a second voltage to the second resonant structure to excite the second resonant structure, the second sense electrode supplying a second signal generated by the second resonant structure in response to rotation of the second resonant structure about the second axis of the second resonant structure

the resonant structure and the second resonant structure being integrated on a common chip.

18. An apparatus, comprising:

a resonant structure formed from a piezoelectric material, a temperature compensated stack, a substrate and having a drive electrode, the resonant structure defining a plane when not excited and defining an axis substantially orthogonal to a plane,

the drive electrode for applying a voltage to the resonant structure to excite the resonating structure in a first mode,

the resonant structure configured to oscillate in a second mode upon rotation about the axis and when excited by the voltage applied to the drive electrode;

the temperature compensated stack located between the piezoelectric material and the substrate; and

the resonant structure being suspended and coupled to the substrate by a plurality of anchors.

19. A method, comprising:

exciting a resonant structure in a first mode, the resonant structure comprising a temperature compensated stack and being suspended and coupled to a substrate by a plurality of anchors; and

measuring an oscillation of the resonant structure upon rotation of the resonant structure and after exciting the resonant structure.

20. The method of claim 19, wherein:

the resonant structure defines a plane when not excited and defines an axis substantially orthogonal to a plane,

the measuring including measuring the oscillation of the resonant structure upon rotation of the resonant structure about the axis and after exciting the resonant structure.