MICROELECTROMECHANICAL GYROSCOPE WITH COMPENSATION OF QUADRATURE SIGNAL COMPONENTS

• US 20140190258A1
• Filed: 01/09/2014
• Published: 07/10/2014
• Est. Priority Date: 01/09/2013
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Donadel, Andrea, Magnoni, Davide, Garbarino, Marco
• Granted Patent: US 9,784,581 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• 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

Abstract

A gyroscope includes: a mass, which is movable with respect to a supporting body; a driving loop for keeping the mass in oscillation according to a driving axis; a reading device, which supplying an output signal indicating an angular speed of the body; and a compensation device, for attenuating spurious signal components in quadrature with respect to a velocity of oscillation of the mass. The reading device includes an amplifier, which supplies a transduction signal indicating a position of the mass according to a sensing axis. The compensation device forms a control loop with the amplifier, extracts from the transduction signal an error signal representing quadrature components in the transduction signal, and supplies to the amplifier a compensation signal such as to attenuate the error signal.

Claims

1. A microelectromechanical gyroscope, comprising:

a supporting body;

a sensing mass elastically coupled to the supporting body and movable with respect to the supporting body according to a driving axis and a sensing axis;

a microelectromechanical driving loop coupled to the sensing mass and operable to maintain the sensing mass in oscillation according to the driving axis at a frequency;

a reading device coupled to the sensing mass and configured to provide an output signal representative of an angular speed of the supporting body, the reading device including a reading amplifier configured to provide a transduction signal representative of a position of the sensing mass according to the sensing axis; and

a compensation device configured to reduce spurious signal components in quadrature with respect to a velocity of oscillation of the sensing mass according to the driving axis, the compensation device being configured to form a feedback control loop with the reading amplifier and configured to extract, from the transduction signal, an error signal representative of quadrature components in the transduction signal and configured to provide the reading amplifier with a compensation signal that is a function of the error signal and is configured to reduce the quadrature components in the transduction signal.

2. The gyroscope according to claim 1 wherein the compensation device includes a compensation demodulator configured to demodulate the transduction signal in quadrature with respect to the velocity of oscillation of the sensing mass.

3. The gyroscope according to claim 2 wherein the microelectromechanical driving loop is configured to provide the compensation demodulator with a compensation conversion signal in quadrature with respect to the velocity of oscillation of the sensing mass.

4. The gyroscope according to claim 2, comprising a compensation low-pass filter cascaded to the compensation demodulator and configured to provide the error signal.

5. The gyroscope according to claim 2 wherein the compensation device includes a compensation modulator configured to modulate the compensation signal in quadrature with respect to the velocity of oscillation of the sensing mass.

6. The gyroscope according to claim 5 wherein the compensation device is coupled to the microelectromechanical driving loop and is configured to obtain a compensation conversion signal in quadrature with respect to the velocity of oscillation of the sensing mass.

7. The gyroscope according to claim 6 wherein the compensation demodulator and the compensation modulator are configured to use the compensation conversion signal to demodulate the transduction signal and to modulate the compensation signal, respectively.

8. The gyroscope according to claim 1 wherein the compensation device includes a control stage configured to provide the compensation signal as a function of the error signal.

9. The gyroscope according to claim 5 wherein the control stage includes a proportional-integral-derivative controller.

10. The gyroscope according to claim 8, comprising a capacitive coupling stage between the control stage and the reading amplifier.

11. The gyroscope according to claim 1 wherein the reading device includes a reading demodulator cascaded to the reading amplifier and configured to demodulate the transduction signal in phase with respect to the velocity of oscillation of the sensing mass.

12. A system, comprising:

a control unit; and

a microelectromechanical gyroscope coupled to the control unit, the gyroscope including;

a driving assembly;

a sensing mass configured to be driven in oscillation by the driving assembly along a driving axis, the driving assembly and the sensing mass configured to form a driving loop configured to maintain the sensing mass in oscillation along the driving axis at a frequency;

a reading assembly coupled to the sensing mass and configured to provide an output signal that represents an angular speed of the system, the reading assembly including;

a reading amplifier configured to provide a transduction signal representative of a position of the sensing mass with respect to a sensing axis; and

a compensation device coupled to the reading amplifier and configured to form a feedback control loop that is configured to extract, from the transduction signal, an error signal representative of quadrature components in the transduction signal and configured to provide the reading amplifier with a compensation signal that is a function of the error signal and is configured to reduce the quadrature components in the transduction signal.

13. The system of claim 12 wherein the reading amplifier is coupled to outputs of the sensing mass and outputs of the compensation device are coupled to the outputs of the sensing device.

14. The system of claim 12 wherein the compensation device includes a demodulator coupled to outputs of the reading amplifier, a low pass filter coupled to the demodulator, a control stage coupled to the low pass filter, and a modulator coupled to control stage, outputs of the control stage being coupled to inputs of the charge amplifier.

15. A method, comprising:

controlling a microelectromechanical gyroscope having a supporting body and a sensing mass, elastically coupled to the supporting body and movable with respect to the supporting body according to a driving axis and a sensing axis, the controlling including;

oscillating the sensing mass according to the driving axis with a frequency;

providing an output signal representative of an angular speed of the supporting body by providing a transduction signal representative of a position of the sensing mass according to the sensing axis; and

reducing spurious signal components in quadrature with respect to a velocity of oscillation of the sensing mass according to the driving axis by extracting, from the transduction signal, an error signal representative of quadrature components in the transduction signal and providing feedback to the reading amplifier with a compensation signal which is a function of the error signal to reduce the quadrature components in the transduction signal.

16. The method according to claim 15 wherein extracting, from the transduction signal, the error signal includes demodulating the transduction signal in quadrature with respect to the velocity of oscillation of the sensing mass.

17. The method according to claim 16 wherein providing feedback to the reading amplifier with the compensation signal includes modulating the compensation signal in quadrature with respect to the velocity of oscillation of the sensing mass.