Drive frequency tunable MEMS gyroscope

• US 8,210,038 B2
• Filed: 02/17/2009
• Issued: 07/03/2012
• Est. Priority Date: 02/17/2009
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Rocznik, Marko
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US12/372,335
• Publication Number:
  US 20100206071A1
• Time in Patent Office: 1,232 Days
• Field of Search: 735/041.2, 735/041.4
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5726 Signal processing
• CPC Class Codes: G01C 19/574 the devices having two sensing masses in anti-phase motion

Abstract

A drive frequency tunable MEMS sensor in one embodiment includes a mass, a mass drive component configured to drive the mass within a plane, a plurality of non-linear springs supporting the mass a first tuner operably connected to the plurality of non-linear springs for modifying the stress condition of the plurality of non-linear springs in response to a trim voltage, and a trim circuit electrically coupled with the first tuner for providing the trim voltage.

Claims

1. A sensor device comprising:

a mass;

a mass drive component configured to drive the mass within a plane along an oscillation axis;

a plurality of non-linear springs supporting the mass;

a first tuner operably connected to the plurality of non-linear springs and configured to modify the stress condition of the plurality of non-linear springs in response to a trim voltage by generating a force along the oscillation axis; and

a trim circuit electrically coupled with the first tuner for providing the trim voltage.

2. The device of claim 1, further comprising a first anchor attached to a substrate, wherein:

a first spring of the plurality of non-linear springs is attached to the first anchor and to a first portion of the first tuner;

a second spring of the plurality of non-linear springs is attached to the mass and to the first portion of the first tuner; and

a second portion of the tuner is fixedly attached to the substrate.

3. The device of claim 2, further comprising:

a second tuner with a first portion and a second portion, the second portion fixedly attached to the substrate;

a second anchor attached to the substrate;

a third spring of the plurality of non-linear springs attached to the second anchor and to the first portion of the second tuner; and

a fourth spring of the plurality of non-linear springs attached to the mass and to the first portion of the second tuner.

4. The device of claim 3, wherein:

the second spring is attached to a first end portion of the mass; and

the fourth spring is attached to a second end portion of the mass, the first end portion of the mass on a side opposite to the second end portion of the mass along the oscillation axis.

5. The device of claim 1, further comprising a first anchor attached to a substrate, wherein:

a first spring of the plurality of non-linear springs is attached to the first anchor and to a first portion of the first tuner;

a second spring of the plurality of non-linear springs is attached to the first portion of the first tuner and to a first portion of a second tuner; and

a third spring of the plurality of non-linear springs is attached to the mass and to the first portion of the second tuner.

6. The device of claim 1, the first tuner comprising:

a first plurality of fingers; and

a second plurality of fingers interlaced with the first plurality of fingers.

7. A method of operating a micro-electromechanical systems (MEMS) device comprising:

supporting a mass above a substrate with a plurality of non-linear springs;

driving the mass within a plane along an oscillation axis;

providing a trim voltage to a first tuner;

generating a force along the oscillation axis with the first tuner; and

modifying the stress condition of the plurality of non-linear springs with the first tuner.

8. The method of claim 7, further comprising:

biasing a first spring of the plurality of non-linear springs toward a first anchor with the first tuner; and

biasing a second spring of the plurality of non-linear springs away from the mass with the first tuner.

9. The method of claim 8, further comprising:

biasing a third spring of the plurality of non-linear springs toward a second anchor with a second tuner; and

biasing a fourth spring of the plurality of non-linear springs away from the mass with the second tuner.

10. The method of claim 9, wherein biasing the fourth spring away from the mass comprises:

biasing the fourth spring toward the second spring.

11. The method of claim 7, further comprising:

modifying the stress condition of the plurality of non-linear springs with a second tuner.

12. The method of claim 7, wherein modifying the stress condition of the plurality of non-linear springs comprises:

applying a voltage to a first plurality of fingers in the first tuner.

13. A micro-electromechanical systems (MEMS) device comprising:

a substrate;

an electrode on the substrate;

a mass positioned above the electrode;

a plurality of non-linear springs supporting the mass above the electrode;

a drive device configured to drive the mass along an oscillation axis in a plane in response to a drive signal; and

at least one tuner physically connected to at least one of the plurality of non-linear springs and configured to modify the stress of the at least one of the plurality of non-linear springs responsive to a trim signal by generating a force along the oscillation axis.

14. The MEMS device of claim 13, wherein:

the plurality of non-linear springs comprises a first spring supporting a first end portion of the mass and a second spring supporting a second end portion of the mass; and

the at least one tuner comprises a first tuner physically connected to the first spring and a second tuner physically connected to the second spring.

15. The MEMS device of claim 14, wherein:

the plurality of non-linear springs comprises a third spring supporting the first end portion of the mass and a fourth spring supporting the second end portion of the mass.

16. The MEMS device of claim 15, wherein:

the at least one tuner comprises a third tuner physically connected to the third spring and a fourth tuner physically connected to the fourth spring.

17. The MEMS device of claim 16, wherein:

the first spring supports a first corner portion of the mass;

the second spring supports a second corner portion of the mass;

the third spring supports a third corner portion of the mass; and

the fourth spring supports a fourth corner portion of the mass.

18. The MEMS device of claim 17, further comprising:

a first anchor fixedly attached to the substrate and supporting the first spring;

a second anchor fixedly attached to the substrate and supporting the second spring;

a third anchor fixedly attached to the substrate and supporting the third spring; and

a fourth anchor fixedly attached to the substrate and supporting the fourth spring.

19. The MEMS device of claim 13, wherein the first tuner comprises:

a first plurality of fingers; and

a second plurality of fingers interlaced with the first plurality of fingers.

20. A sensor device comprising:

a mass;

a mass drive component configured to drive the mass within a plane;

an anchor attached to a substrate;

a first non-linear spring attached to the anchor and to a first portion of a first tuner, the first tuner configured to modify the stress condition of the first non-linear spring in response to a first trim voltage;

a second non-linear spring attached to the first portion of the first tuner and to a first portion of a second tuner, the second tuner configured to modify the stress condition of the second non-linear spring in response to a second trim voltage;

a third spring attached to the mass and to the first portion of the second tuner; and

a trim circuit electrically coupled with the first tuner for providing the first trim voltage, and with the second tuner for providing the second trim voltage.