PIEZOELECTRIC ACCELEROMETER

• US 20200132540A1
• Filed: 10/29/2019
• Published: 04/30/2020
• Est. Priority Date: 10/30/2018
• Status: Active Application

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: SUMMERFELT, Scott Robert, MOTIEIAN NAJAR, Mohammad Hadi, SMEYS, Peter
• Application Number:
  US16/667,507
• Publication Number:
  US 20200132540A1
• Time in Patent Office: Days
• CPC Class Codes: G01H 11/08 using piezoelectric devices
• CPC Class Codes: G01P 15/09 by piezoelectric pick-up
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/135 by making use of contacts which are actuated by a movable inertial mass
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/084 the mass being suspended at more than one of its sides, e.g. membrane-type suspension, so as to permit multi-axis movement of the mass
• CPC Class Codes: G01P 2015/0871 using stopper structures for limiting the travel of the seismic mass
• CPC Class Codes: H10N 30/302 Sensors
• CPC Class Codes: H10N 30/40 with electrical input and electrical output, e.g. functioning as transformers
• CPC Class Codes: H10N 30/802 Circuitry or processes for operating piezoelectric or electrostrictive devices not otherwise provided for, e.g. drive circuits
• CPC Class Codes: H10N 30/87 Electrodes or interconnections, e.g. leads or terminals

Abstract

An acceleration change sensor includes a flexible member comprising extensions extending from a central portion. Piezoelectric capacitors are provided on respective extensions. A proof mass is coupled to the flexible member and offset from each extension of the plurality of extensions.

Claims

1. An integrated circuit (IC), comprising:

a flexible plate comprising a first pair of arms and a second pair of arms, the first pair orthogonal to the second pair;

piezoelectric capacitors on each of respective arms of the first pair and on each of the arms of the second pair; and

a proof mass coupled to the flexible plate and offset from the first and second pair of arms.

2. The IC of claim 1, wherein each arm of the first and second pair of arms is trapezoidal from an outside edge of the arm towards a center of the arm.

3. The IC of claim 1, wherein the arms of the first pair of arms have opposing ends and are tapered between the opposing ends.

4. The IC of claim 1, wherein the proof mass comprises silicon.

5. The IC of claim 1, wherein the arms of the first pair are parallel to each other, and the arms of the second pair are parallel to each other.

6. The IC of claim 1, wherein the proof mass resides at least partially within a cavity of the IC, and the IC further includes a cap on a side of the flexible plate opposite the proof mass.

7. The IC of claim 1, further comprising reference piezoelectric capacitors, wherein the piezoelectric capacitors on the arms are subject to strain as the proof mass moves due to acceleration, but the reference capacitors are arranged so as not to be subject to the strain.

8. The IC of claim 1, further comprising pre-amplifiers coupled to the piezoelectric capacitors, the pre-amplifiers configured to provide a three-axis measurement of changes in acceleration.

9. The IC of claim 1, wherein the flexible plate comprises silicon dioxide.

10. An acceleration change sensor, comprising:

a flexible member comprising first and second extensions extending from a central portion;

piezoelectric capacitors on each of the first and second extensions of the plurality of extensions; and

a proof mass coupled to the flexible member and offset from each of the first and second extensions.

11. The acceleration change sensor of claim 10, wherein the flexible member comprises at least one of silicon dioxide or silicon nitride and the proof mass comprises silicon.

12. The acceleration change sensor of claim 10, wherein the flexible member comprises four extensions.

13. The acceleration change sensor of claim 12, wherein:

the four extensions comprise the first and extensions as well as third and fourth extensions;

the first and second extensions are parallel to each other; and

the third and fourth extensions are parallel to each other.

14. The acceleration change sensor of claim 13, wherein the first and second extensions are orthogonal to the third and fourth extensions.

15. The acceleration change sensor of claim 10, wherein each extension of the four extensions is trapezoidal from an edge towards a center of the extension.

16. The acceleration change sensor of claim 10, wherein each extension of the four extensions has opposing ends and is tapered between the opposing ends.

17. An integrated circuit (IC), comprising:

a flexible plate comprising a first pair of arms and a second pair of arms, the first pair orthogonal to the second pair;

piezoelectric capacitors on each of the arms of the first pair and on each of the arms of the second pair;

a proof mass coupled to the flexible plate and offset from the first and second pair of arms, the proof mass at least partially residing within a cavity; and

a cap on a side of the flexible plate opposite the proof mass;

wherein the piezoelectric capacitors are configured to be subject to strain upon movement of the proof mass within the cavity.

18. The IC of claim 17, wherein the arms of the first pair of arms have opposing ends and are tapered between the opposing ends.

19. The IC of claim 17, further comprising reference piezoelectric capacitors, wherein the reference capacitors are arranged so as not to be subject to the strain upon movement of the proof mass.

20. The IC of claim 17, wherein the flexible plate comprises silicon dioxide and the proof mass comprises silicon.