Microelectromechanical gyroscope with compensation of quadrature signal components

• US 9,784,581 B2
• Filed: 01/09/2014
• Issued: 10/10/2017
• 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
• Primary Examiner(s): MacChiarolo, Peter
• Assistant Examiner(s): Singer, David L
• Application Number:
  US14/151,426
• Publication Number:
  US 20140190258A1
• Time in Patent Office: 1,370 Days
• Field of Search: 7350402, 7350404, 7350412-50416, 324 7678- 7679
• 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 driving device coupled to the sensing mass by a microelectromechanical driving loop operable to generate a driving signal and to maintain the sensing mass in oscillation according to the driving axis at a driving frequency based on the driving signal, the driving device including a clock generator that generates and outputs a compensation conversion signal and a reading conversion signal, each of the driving signal, the compensation conversion signal, and the reading conversion signal separate signals output by the driving device;

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,

wherein the compensation device includes a compensation demodulator coupled to the clock generator and configured to receive the compensation conversion signal and demodulate the transduction signal based on the compensation conversion signal, in quadrature with respect to the velocity of oscillation of the sensing mass according to the driving axis, a compensation low-pass filter cascaded to the compensation demodulator and configured to suppress signal components at twice the frequency of the driving frequency, a control stage coupled to the low-pass filter, and a compensation modulator coupled to the control stage and to the clock generator, the compensation modulator being configured to receive the compensation conversion signal and to modulate an output of the control stage based on the compensation conversion signal.

2. The gyroscope according to claim 1 wherein the microelectromechanical driving loop is configured to provide the compensation demodulator with the compensation conversion signal in quadrature with respect to the velocity of oscillation of the sensing mass.

3. The gyroscope according to claim 1, wherein the compensation low-pass filter is configured to provide the error signal.

4. The gyroscope according to claim 1 wherein the compensation modulator is configured to modulate the compensation signal in quadrature with respect to the velocity of oscillation of the sensing mass.

5. The gyroscope according to claim 4 wherein the compensation device is coupled to the microelectromechanical driving loop and is configured to obtain the compensation conversion signal in quadrature with respect to the velocity of oscillation of the sensing mass.

6. The gyroscope according to claim 5 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.

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

8. The gyroscope according to claim 7 wherein the control stage includes a proportional-integral-derivative controller.

9. The gyroscope according to claim 7, comprising a capacitive coupling stage between the control stage and the reading amplifier.

10. 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.

17. The microelectromechanical gyroscope according to claim 1 wherein the driving device includes an oscillator coupled to the clock generator, the clock generator being configured to generate the compensation conversion signal and the reading conversion signal based on an output of the oscillator.

18. The microelectromechanical gyroscope according to claim 1 wherein the clock generator is configured to generate the compensation conversion signal and the reading conversion signal at the driving frequency.

11. A system, comprising:

a control unit; and

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

a driving assembly including a clock generator configured to generate and output a compensation conversion signal, a reading conversion signal, and a driving signal, each of the compensation conversion signal, the reading conversion signal, and the driving signal are separate signals output by the driving assembly;

a sensing mass configured to be driven by the driving signal 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 driving 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 extracts, from the transduction signal, an error signal representative of quadrature components in the transduction signal and provides the reading amplifier with a compensation signal that is a function of the error signal, the compensation device reduces the quadrature components in the transduction signal,

wherein the compensation device includes a compensation demodulator coupled to outputs of the reading amplifier and to the clock generator, the compensation demodulator being configured to receive the compensation conversion signal and demodulate the transduction signal based on the compensation conversion signal, in quadrature with respect to the velocity of oscillation of the sensing mass according to the driving axis, a compensation low-pass filter cascaded to the compensation demodulator and configured to suppress signal components at twice the frequency of the driving frequency, a control stage coupled to the low-pass filter, and a compensation modulator coupled to the control stage and to the clock generator, the compensation modulator being configured to receive the compensation conversion signal and to modulate an output of the control stage based on the compensation conversion signal.

12. The system of claim 11 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 mass.

19. The system according to claim 11 wherein the driving device includes an oscillator coupled to the clock generator, the clock generator being configured to generate the compensation conversion signal and the reading conversion signal based on an output of the oscillator.

20. The system according to claim 11 wherein the clock generator is configured to generate the compensation conversion signal and the reading conversion signal at the driving frequency.

13. 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;

generating, by a clock generator in a driving device, a compensation conversion signal and a reading conversion signal;

generating, by the driving device, a driving signal, each of the compensation conversion signal, the reading conversion signal, and the driving signal being separate signal;

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

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

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 by demodulating the transduction signal, based on the compensation conversion signal, in quadrature with respect to the velocity of oscillation of the sensing mass according to the driving axis and suppressing signal components at twice the frequency of the driving frequency;

generating, by a control stage, a compensation signal based on the error signal;

modulating the compensation signal based on the compensation conversion signal to generate a modulated compensation signal; and

providing the modulated compensation signal as feedback to the reading amplifier to reduce the quadrature components in the transduction signal.

14. The method according to claim 13 wherein modulating the compensation signal includes modulating the compensation signal in quadrature with respect to the velocity of oscillation of the sensing mass.

15. The method according to claim 13, further comprising demodulating the transduction signal based on the reading conversion signal.

16. The method according to claim 13 further comprising:

generating, by an oscillator coupled to the clock generator, an auxiliary clock signal having a calibrated frequency substantially equal to the driving frequency, wherein generating the compensation conversion signal and the reading conversion signal includes generating the compensation conversion signal and the reading conversion signal based on the auxiliary clock signal.