QUAD PROOF MASS MEMS GYROSCOPE WITH OUTER COUPLERS AND RELATED METHODS

• US 20180058853A1
• Filed: 08/31/2016
• Published: 03/01/2018
• Est. Priority Date: 08/31/2016
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Jia, Kemiao, Zhang, Xin, Zhang, Jianglong, Kuang, Jinbo
• Granted Patent: US 10,514,259 B2
• Time in Patent Office: Days
• CPC Class Codes: G01C 19/5705 using masses driven in reciprocating rotary motion about an axis
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure

Abstract

A two-axis microelectromechanical systems (MEMS) gyroscope having four proof masses disposed in respective quadrants of a plane is described. The quad proof mass gyroscope may comprise an inner coupler passing between a first and a third proof mass and between a second and a fourth proof mass, and coupling the four proof masses with one another. The quad proof mass gyroscope may further comprising a first outer coupler coupling the first and the second proof masses and a second outer coupler coupling the third and the fourth proof masses. The outer couplers may have masses configured to balance the center of masses of the four proof masses, and may have elastic constants matching the elastic constant of the inner coupler. The quad gyroscope may further comprise a plurality of sense capacitors configured to sense angular rates.

Claims

1. A microelectromechanical systems (MEMS) gyroscope comprising:

four proof masses disposed in respective quadrants of a plane and each configured to resonate, the first proof mass and the second proof mass being configured to resonate in-phase;

a first outer coupler coupling the first and second proof masses of the four proof masses;

a second outer coupler coupling third and fourth proof masses of the four proof masses; and

an inner coupler passing between the first and third proof masses and between the second and fourth proof masses and coupling the four proof masses with one another.

2. The MEMS gyroscope of claim 1, wherein the third and fourth proof masses are configured to resonate in-phase.

3. The MEMS gyroscope of claim 2, wherein the first and third proof masses are configured to resonate out-of-phase.

4. The MEMS gyroscope of claim 1, wherein the MEMS gyroscope lacks outer couplers coupling the first and third proof masses to each other and the second and fourth proof masses to each other.

5. The MEMS gyroscope of claim 1, wherein the first outer coupler, the second outer coupler and the inner coupler are substantially parallel to one another.

6. The MEMS gyroscope of claim 1, further comprising a sense electrode disposed on a substrate of the MEMS gyroscope and forming a sense capacitor with a portion of the first proof mass.

7. The MEMS gyroscope of claim 1, wherein the first outer coupler and the second outer coupler have approximately equal masses.

8. The MEMS gyroscope of claim 1, wherein the inner coupler comprises a first beam connecting the first proof mass to the second proof mass, a second beam connecting the third proof mass to the fourth proof mass, and a third beam connecting the first beam to the second beam.

9. The MEMS gyroscope of claim 1, wherein each of the four proof masses is configured to rotate within the plane.

10. The MEMS gyroscope of claim 1, wherein the first and the second outer couplers are symmetrically disposed with respect to the inner coupler.

11. A system comprising:

four proof masses disposed in respective quadrants of a plane and each configured to rotate within the plane, the first proof mass and the second proof mass being configured to resonate in-phase;

a first outer coupler coupling the first and second proof masses of the four proof masses;

a second outer coupler coupling third and fourth proof masses of the four proof masses;

an inner coupler passing between the first and third proof masses and between the second and fourth proof masses and coupling the four proof masses with one another;

a sense electrode disposed on a substrate of the MEMS gyroscope and forming a sense capacitor with a portion of the first proof mass; and

sense circuitry coupled to the sense capacitor and configured to digitize angular rate data for at least one of the four proof masses.

12. The system of claim 11, further comprising an I/O interface coupled to the sense circuitry and configured to transmit the digitized angular rate data to a monitoring station disposed external to the system.

13. The system of claim 11, further comprising a display coupled to the sense circuitry and configured to display an image corresponding to the digitized angular rate data.

14. The system of claim 11, wherein the inner coupler, the first outer coupler and the second outer coupler are substantially parallel to each other.

15. The system of claim 11, wherein the third and fourth proof masses are configured to resonate in-phase.

16. The system of claim 15, wherein the first and third proof masses are configured to resonate out-of-phase.

17. A device comprising the system of claim of 11 and a mechanical stabilizer coupled to the sense circuitry and configured to stabilize the device in response to the angular rate data.

18. A method of operating a microelectromechanical systems (MEMS) gyroscope comprising four proof masses disposed in respective quadrants of a plane, the method comprising:

causing the first proof mass and the third proof mass to resonate in-phase with respect to each other by constraining motion of the first proof mass and the third proof mass with a first outer coupler;

causing the first proof mass and the second proof mass to resonate out-of-phase with respect to each other by constraining motion of the first proof mass and the second proof mass with an inner coupler; and

detecting angular rate of at least one of the four proof masses by sensing motion of the at least one of the four proof masses along a direction perpendicular to the plane.

19. The method of claim 18, further comprising causing the second proof mass and the fourth proof mass to resonate in-phase with respect to each other by constraining motion of the second proof mass and the fourth proof mass with a second outer coupler.

20. The method of claim 18, wherein the inner coupler passes between the first and third proof masses and between the second and fourth proof masses and is configured to couple the four proof masses with one another.