MICROELECTROMECHANICAL GYROSCOPES AND RELATED APPARATUS AND METHODS

• US 20140137648A1
• Filed: 01/28/2014
• Published: 05/22/2014
• Est. Priority Date: 03/01/2010
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Sand 9, Inc. (Analog Devices, Inc.)
• Inventors: Zolfagharkhani, Guiti, Kuypers, Jan H., Gaidarzhy, Alexei, Chen, David M., Mohanty, Pritiraj
• Granted Patent: US 9,651,376 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure

Abstract

In one embodiment, an apparatus comprises a micromechanical gyroscope and a circuit. The micromechanical gyroscope is configured to be excited in a first mode by a drive signal, and configured to be excited in a second mode by a gyroscopic effect. The circuit is coupled to the micromechanical gyroscope and configured to detect the gyroscopic effect when the micromechanical gyroscope is in the second mode.

Claims

1. An apparatus, comprising:

a substrate having a plate that is excitable by a gyroscopic effect, wherein the plate includes a temperature-compensated stack having first and third layers that have a stiffness that increases with increasing temperature over a temperature range with a second layer between the first and third layers, wherein the second layer is formed from a different material than the first and third layers.

2. The apparatus of claim 1, further comprising:

a circuit configured to detect the gyroscopic effect.

3. The apparatus of claim 1, further comprising:

a piezoelectric layer included with the plate, the piezoelectric layer being made of at least one of aluminum nitride, zinc oxide, lead zirconate titanate (PZT), lithium niobate (LiNbO3), potassium niobate (KNbO3), lithium tantanate (LiTaO3), quartz, barium strontium titanate (Ba Sr TiO3) or manganese niobium titanate (MnNbTiO3).

4. The apparatus of claim 1, wherein the plate is made of at least one of silicon or silicon oxide.

5. The apparatus of claim 1, wherein the plate includes at least one piezoelectric thin film.

6. The apparatus of claim 1, wherein the plate includes a first piezoelectric thin film, a second piezoelectric thin film, and an electrode layer disposed between the first piezoelectric thin film and the second piezoelectric thin film.

7. The apparatus of claim 1, wherein the substrate is unpatterned and conductive.

8. An apparatus, comprising:

a substrate;

a member moveably coupled to the substrate at a first anchor and a second anchor, the member being excitable by a gyroscopic effect, wherein the member includes a temperature-compensated stack having first and third layers that have a stiffness that increases with increasing temperature over a temperature range with a second layer between the first and third layers, wherein the second layer is formed from a different material than the first and third layers; and

a circuit coupled to the member and configured to detect the gyroscopic effect.

9. The apparatus of claim 8, further comprising:

a piezoelectric layer included with the member, the piezoelectric layer being made of at least one of aluminum nitride, zinc oxide, lead zirconate titanate (PZT), lithium niobate (LiNbO3), potassium niobate (KNbO3), lithium tantanate (LiTaO3), quartz, barium strontium titanate (BaSrTiO3) or manganese niobium titanate (MnNbTiO3).

10. The apparatus of claim 8, wherein the member is made of at least one of silicon or silicon oxide.

11. The apparatus of claim 8, wherein the member includes at least one piezoelectric thin film.

12. The apparatus of claim 8, wherein the member includes a first piezoelectric thin film, a second piezoelectric thin film, and an electrode layer disposed between the first piezoelectric thin film and the second piezoelectric thin film.

13. An apparatus, comprising:

a micromechanical gyroscope configured to be excited by a gyroscopic effect, wherein the micromechanical gyroscope includes a temperature-compensated stack having a first layer of first material that has a stiffness that increases with increasing temperature over a temperature range and a second layer of second material that is different from the first material; and

a circuit coupled to the micromechanical gyroscope and configured to detect the gyroscopic effect.

14. The apparatus of claim 13, wherein the second material has lower acoustical loss characteristics than the first material

15. The apparatus of claim 13, wherein the circuit provides a positive gain feedback loop when a drive signal is applied to the micromechanical gyroscope.

16. The apparatus of claim 13, wherein the first material comprises silicon dioxide.

17. The apparatus of claim 13, wherein the second material comprises silicon, diamond, silicon carbide, sapphire, quartz, germanium, aluminum nitride, or gallium arsenide.

18. The apparatus of claim 13, further comprising:

a mixer coupled to the micromechanical gyroscope.

19. The apparatus of claim 18, further comprising:

a low-pass filter coupled to the mixer, the low-pass filter configured to output an output voltage responsive to a drive signal being applied to the micromechanical gyroscope.

20. The apparatus of claim 13, further comprising:

a first piezoelectric thin film, a second piezoelectric thin film, and an electrode layer disposed between the first piezoelectric thin film and the second piezoelectric thin film.