MEMS DEVICE QUADRATURE SHIFT CANCELLATION

• US 20130268228A1
• Filed: 04/05/2013
• Published: 10/10/2013
• Est. Priority Date: 04/05/2012
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Fairchild Semiconductor Corporation (ON Semiconductor Corporation)
• Inventors: Opris, Ion, Tao, Hai, Lee, Shungneng
• Granted Patent: US 10,060,757 B2
• Time in Patent Office: Days
• US Class Current: 702/104
• CPC Class Codes: G01C 19/5726 Signal processing
• CPC Class Codes: G01C 19/5776 Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719
• CPC Class Codes: G01C 25/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass testing, calibrating or compensating compasses G01C17/38

Abstract

This document discusses, among other things, apparatus and methods quadrature cancelation of sense information from a micro-electromechanical system (MEMS) device, such as a MEMS gyroscope. In certain examples, a quadrature correction apparatus can include a drive charge-to-voltage (C2V) converter configured to provide drive information of a proof mass of a MEMS gyroscope, a sense C2V converter configured to provide sense information of the proof mass, a phase-shift module configured to provide phase shift information of the drive information, a drive demodulator configured to receive the drive information and the phase shift information and to provide demodulated drive information, a sense demodulator configured to receive the sense information and the phase shift information and to provide demodulated sense information, and wherein the quadrature correction apparatus is configured to provide corrected sense information using the demodulated drive information and the demodulated sense information.

Claims

1. A quadrature correction apparatus comprising:

a drive charge-to-voltage (C2V) converter configured to provide drive information of a proof mass of a MEMS gyroscope;

a sense C2V converter configured to provide sense information of the proof mass;

a phase-shift module configured to provide phase shift information of the drive information;

a drive demodulator configured to receive the drive information and the phase shift information and to provide demodulated drive information;

a sense demodulator configured to receive the sense information and the phase shift information and to provide demodulated sense information; and

wherein the quadrature correction apparatus is configured to provide corrected sense information using the demodulated drive information and the demodulated sense information.

2. The apparatus of claim 1, including:

a summing node configured to provide the corrected sense information using the demodulated drive information and the demodulated sense information.

3. The apparatus of claim 1, including:

a correction amplifier configured to receive the demodulated drive information and to provide amplified demodulated drive information;

wherein the quadrature correction apparatus is configured to provide the corrected sense information using the amplified demodulated drive information and the demodulated sense information.

4. The apparatus of claim 3, including:

a summing node configured to provide the corrected sense information using the amplified demodulated drive information and the demodulated sense information.

5. The apparatus of claim 1, including an analog-to-digital converter configured to receive the corrected sense signal and to provide a digital representation of the corrected sense signal.

6. The apparatus of claim 1, wherein the drive demodulator includes a first analog-to-digital converter configured to receive the demodulated drive signal and to provide a digital representation of the demodulated drive signal.

7. The apparatus of claim 6, wherein the drive demodulator includes a correction amplifier configured to adjust a level of the digital representation of the demodulated drive signal to provide a correction signal to cancel the quadrature error of the sensed information.

8. The apparatus of claim 7, wherein the sense demodulator includes a second analog-to-digital converter configured to receive the demodulated sense signal and to provide a digital representation of the demodulated sense signal.

9. The apparatus of claim 8, wherein the summing node includes a digital summing node configured to combine the digital representation of the demodulated drive signal and the digital representation of the demodulated sense signal to cancel quadrature error of the demodulated sense signal, and to provide a digital, corrected sense signal.

10. A method comprising:

providing drive information of a proof mass of a MEMS gyroscope using a drive charge-to-voltage (C2V) converter;

providing sense information of the proof mass using a sense C2V converter;

providing phase shift information of the drive information using the drive information and a phase-shift module;

demodulating the drive information using a drive demodulator and the phase shift information to provide demodulated drive information;

demodulating the sense information using a sense demodulator and the phase shift information to provide demodulated sense information; and

canceling quadrature error of the sense information to provide a corrected sense signal using the demodulated drive information and the demodulated sense information.

11. The method of claim 10, including adjusting a level of the demodulated drive information using a correction amplifier

12. The method of claim 11, including converting the corrected sense signal using an analog-to-digital converter to provide a digital representation of the corrected sense signal.

13. The method of claim 10, including providing a digital representation of the demodulated drive signal using the demodulated drive information and a first analog-to-digital converter.

14. The method of claim 13, including adjusting a level of the digital representation of the demodulated drive information using a correction amplifier.

15. The method of claim 14, including providing a digital representation of the demodulated sense signal using the demodulated sense information and a second analog-to-digital converter.

16. The method of claim 15, wherein the canceling quadrature error includes digitally summing the digital representation of the demodulated drive signal and the digital representation of the demodulated sense signal to provide a digital, corrected sense signal.

17. A system comprising:

a MEMS device including a proof mass;

a control circuit configured to provide sense information of the proof mass, the control circuit including;

a drive charge-to voltage (C2V) converter configured to couple to the proof mass and to provide drive information of the proof mass;

a sense C2V converter configured to receive a sense signal from the proof mass and to provide sense information of the proof mass;

a phase-shift module configured provide phase shift information using the drive information;

a drive demodulator configured to receive phase shift information and an the drive information to provide a demodulated drive signal;

a sense demodulator configured to the phase shift information and the sense information to provide a demodulated sense signal;

a summing node configured to cancel quadrature error of the sense information and to provide a corrected sense signal using a sum of the demodulated drive signal and the demodulated sense signal.

18. The system of claim 17, wherein the drive demodulator includes a correction amplifier configured to adjust a level of the demodulated drive signal to provide a correction signal to cancel the quadrature error of the sense information;

and

an analog to digital converter configured to receive the corrected sense signal and to provide a digital representation of the corrected sense signal.

19. The system of claim 17, wherein the drive demodulator includes a first analog-to-digital converter configured to receive the demodulated drive signal and to provide a digital representation of the demodulated drive signal;

and

wherein the drive demodulator includes a digital correction amplifier configured to adjust a level of the digital representation of the demodulated drive signal to provide a digital correction signal to cancel the quadrature error of the sensed information.

20. The apparatus of claim 19, wherein the sense demodulator includes a second analog-to-digital converter configured to receive the demodulated sense signal and to provide a digital representation of the demodulated sense signal.

21. The apparatus of claim 20, wherein the summing node includes a digital summing node configured to combine the digital representation of the demodulated drive signal and the digital representation of the demodulated sense signal to cancel quadrature error of the demodulated sense signal, and to provide a digital, corrected sense signal.