Reducing resonance peaks and drive tones from a micro-electro-mechanical system gyroscope response

• US 9,885,577 B2
• Filed: 07/30/2015
• Issued: 02/06/2018
• Est. Priority Date: 07/30/2015
• Status: Active Grant

• Current Assignee: Invensense Incorporated (TDK Corporation)
• Original Assignee: Invensense Incorporated (TDK Corporation)
• Inventors: Tsinker, Vadim
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US14/814,016
• Publication Number:
  US 20170030714A1
• Time in Patent Office: 922 Days
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01C 19/5776 Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719

Abstract

Reducing noise from drive tone and sense resonance peaks of a micro-electro-mechanical system (MEMS) gyroscope output using a notch filter is presented herein. The MEMS gyroscope can include a drive oscillation component configured to vibrate a sensor mass at a drive resonance frequency; a sense circuit configured to detect a deflection of the sensor mass, and generate, based on the deflection and the drive resonance frequency, a demodulated output; and a signal processing component configured to receive a set of frequencies comprising a first value representing the drive resonance frequency and a second value corresponding to a sense resonance frequency associated with the sense circuit, and apply, based on the first value and the second value, a notch filter to the demodulated output to obtain a filtered output.

Claims

1. A micro-electro-mechanical system (MEMS) gyroscope, comprising:

a drive oscillation component configured to vibrate a sensor mass at a drive resonance frequency;

a sense circuit configured to;

detect a deflection of the sensor mass; and

generate, based on the deflection and the drive resonance frequency, a demodulated output; and

a signal processing component configured to;

receive a set of frequencies comprising a first value representing the drive resonance frequency, a second value corresponding to a sense resonance frequency associated with the sense circuit, and tone values representing tones of the drive resonance frequency, and

apply, based on the first value the second value, and the tone values, a notch filter to the demodulated output to obtain a filtered output.

2. The MEMS gyroscope of claim 1, wherein the drive resonance frequency corresponds to a resonant frequency of the sensor mass.

3. The MEMS gyroscope of claim 2, wherein the drive oscillation component is further configured to generate mechanical resonance of the sensor mass at the drive resonance frequency.

4. The MEMS gyroscope of claim 1, wherein the sense circuit is further configured to detect a displacement of the sensor mass corresponding to a coriolis force.

5. The MEMS gyroscope of claim 4, wherein the sense circuit is further configured to determine a change in capacitance of a sensor that has been capacitively coupled to the sensor mass.

6. The MEMS gyroscope of claim 5, wherein the sense circuit is further configured to:

generate, based on the change in capacitance, a deflection output;

amplify the deflection output using a charge-to-voltage amplifier to obtain an amplified output; and

demodulate, based on the drive resonance frequency, the amplified output to obtain the demodulated output.

7. The MEMS gyroscope of claim 1, wherein the sense circuit is further configured to:

convert the demodulated output to a digital value utilizing an analog-to-digital converter.

8. The MEMS gyroscope of claim 7, wherein the signal processing component is further configured to apply the notch filter to the digital value to obtain the filtered output.

9. The MEMS gyroscope of claim 1, wherein the signal processing component is further configured to apply a low pass filter to the filtered output.

10. A method, comprising:

vibrating, by a drive oscillation component of a micro-electro-mechanical system (MEMS) gyroscope, a sensor mass of the MEMS gyroscope at a drive resonance frequency;

detecting, by a sense circuit of the MEMS gyroscope, a deflection of the sensor mass;

generating, by the sense circuit based on the deflection and the drive resonance frequency, a demodulated output; and

in response to receiving, by a signal processing component of the MEMS gyroscope, a set of frequencies from a system, the set of frequencies comprising a first value representing the drive resonance frequency a second value corresponding to a sense resonance frequency associated with the sense circuit, and a group of values representing integer multiples of the drive resonance frequency,

applying, by the signal processing component based on the first value, the second value, and the group of values, a notch filter to the demodulated output to obtain a filtered output.

11. The method of claim 10, wherein the drive resonance frequency corresponds to a resonant frequency of the sensor mass.

12. The method of claim 11, wherein the vibrating of the sensor mass comprises generating, by the drive oscillation component, mechanical resonance of the sensor mass at the drive resonance frequency.

13. The method of claim 10, wherein the detecting of the deflection comprises detecting, by the sense circuit, a displacement of the sensor mass corresponding to a coriolis force.

14. The method of claim 13, wherein the detecting of the displacement comprises determining a change in capacitance of a sensor that is capacitively coupled to the sensor mass.

15. The method of claim 14, wherein the generating of the demodulated output comprises:

amplifying a deflection output representing the change in capacitance using a charge-to-voltage amplifier to obtain an amplified output; and

demodulating, based on the drive resonance frequency, the amplified output to obtain the demodulated output.

16. The method of claim 10, wherein the generating of the demodulated output comprises converting the demodulated output to a digital value utilizing an analog-to-digital converter.

17. The method of claim 16 wherein the applying of the notch filter comprises applying the notch filter to the digital value to obtain the filtered output.

18. The method of claim 10, further comprising:

applying, by the signal processing component, a low pass filter to the filtered output.

19. A system, comprising:

a frequency identification component configured to;

determine a drive resonance frequency corresponding to a vibration of a sensor mass of a MEMS gyroscope; and

determine a sense resonance frequency of a sense circuit of the MEMS gyroscope; and

a programming component configured to;

store the drive resonance frequency a value corresponding to the sense resonance frequency, and tones of the drive resonance frequency in a memory to facilitate an application, by the MEMS gyroscope using the drive resonance frequency, the value corresponding to the sense resonance frequency, and the tones of the drive resonance frequency, of a notch filter to a demodulated output corresponding to a coriolis force associated with a deflection of the sensor mass of the MEMS gyroscope.

20. The system of claim 19, wherein the value represents at least one of the sense resonance frequency or a difference between the sense resonance frequency and the drive resonance frequency.

21. The system of claim 19, wherein the frequency identification component is further configured to:

determine drive resonance frequencies corresponding to sensor masses of respective axes of the MEMS gyroscope, wherein the drive resonance frequencies comprise the drive resonance frequency, and wherein the sensor masses comprise the sensor mass; and

determine sense resonance frequencies of sensors corresponding to the sensor masses, wherein the sense resonance frequencies comprise the sense resonance frequency, and wherein the sense circuit comprises the sensors.

22. The system of claim 21, wherein the programming component is further configured to:

store the drive resonance frequencies and values corresponding to the sense resonance frequencies in the memory to facilitate use, by the MEMS gyroscope, of notch filters according to the drive resonance frequencies and the values corresponding to the sense resonance frequencies, wherein the values comprises the value, and wherein the notch filters comprise the notch filter.