Reading circuit for MEMS gyroscope having inclined detection directions

• US 8,813,565 B2
• Filed: 03/07/2013
• Issued: 08/26/2014
• Est. Priority Date: 11/26/2008
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Caminada, Carlo, Prandi, Luciano
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US13/789,496
• Publication Number:
  US 20130180331A1
• Time in Patent Office: 537 Days
• Field of Search: 735/041.2, 735/10
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure

Abstract

A multi-axis gyroscope includes a microelectromechanical structure configured to rotate with respective angular velocities about respective reference axes, and including detection elements, which are sensitive in respective detection directions and generate respective detection quantities as a function of projections of the angular velocities in the detection directions. The gyroscope including a reading circuit that generates electrical output signals, each correlated to a respective one of the angular velocities, as a function of the detection quantities. The reading circuit includes a combination stage that combines electrically with respect to one another electrical quantities correlated to detection quantities generated by detection elements sensitive to detection directions different from one another, so as to take into account a non-zero angle of inclination of the detection directions with respect to the reference axes.

Claims

1. A device, comprising:

a multi-axis gyroscope configured to rotate in response to angular velocities about a first axis and a second axis, the gyroscope including;

a first pair of detection elements, each detection element being configured to detect rotation about the first axis and the second axis, the first pair of detection elements being aligned with each other along a third axis at a non-zero angle of inclination with respect to the first and second axes, the first pair being configured to generate a first set of detection signals;

a second pair of detection elements, each detection element being configured to detect rotation about the first axis and the second axis, the second pair of detection elements being aligned with each other along a fourth axis different from the third axis, the fourth axis being at a non-zero angle of inclination from the first and second axes, the second pair being configured to generate a second set of detection signals;

a reading circuit coupled to the gyroscope, the reading circuit including;

a combination stage configured to combine the first and second sets of detection signals to produce a first combination signal and a second combination signal, the combination stage configured to account for the non-zero angle of inclination of the third and fourth axes, the combination stage is configured to receive timing signals to short circuit in pairs one of the detection elements from the first pair and one of the detection elements from the second pair; and

an output stage configured to provide a first and a second electrical output signal based on the first and second combination signals received from the combination stage, the first output signal being correlated to the angular velocity about the first axis and the second output signal being correlated to the angular velocity about the second axis.

2. The device of claim 1, wherein the reading circuit includes a plurality of inputs electrically connected between outputs from the gyroscope and inputs of the combination stage.

3. The device of claim 1, wherein the timing signals include a first timing signal and a second timing signal, the combination stage including a plurality of switches configured to receive the first and second timing signals, the plurality of switches being configured to short circuit one of the detection elements from the first pair and one of the detection elements from the second pair in response to the first timing signal and to short circuit the other one of the detection elements from the first pair and the other one of the detection elements from the second pair in response to the second timing signal.

4. The device of claim 3, wherein the first pair and the second pair of detection elements are capacitive detection elements and the combination stage is configured to generate a first combination of charge contributions in response to the first timing signal and a second combination of charge contributions in response to the second timing signal.

5. A device, comprising:

a rectangular frame, the frame having a first side that extends along a first axis and a second side that extends along a second axis, the second axis being transverse to the first axis;

a first pair of sensing electrodes within the frame, the first pair of sensing electrodes being aligned with each other along a third axis that is transverse to the first and the second axis, each sensing electrode of the first pair being configured to detect rotations about the first axis and the second axis;

a second pair of sensing electrodes within the frame, the second pair of sensing electrodes being aligned with each other along a fourth axis that is transverse to the third axis, each sensing electrode of the second pair being configured to detect rotations about the first and the second axis; and

a reading circuit coupled to the first pair and the second pair of sensing electrodes, the reading circuit being configured to output a first output signal corresponding to rotations about the first axis and a second output signal corresponding to rotations about the second axis the reading circuit being configured to receive timing signals to turn off in pairs one of the sensing electrodes from the first pair and one of the sensing electrodes from the second pair.

6. The device of claim 5 wherein:

the first pair of sensing electrodes is configured to output a first sensing signal and a second sensing signal, each of the first and second sensing signals having a component associated with rotations about the first axis and a component associated with rotations about the second axis; and

the second pair of sensing electrodes is configured to output a third sensing signal and a fourth sensing signal, each of the third and fourth sensing signals having a component associated with rotations about the first axis and a component associated with rotations about the second axis.

7. The device of claim 6 wherein the reading circuit is configured to receive the first, second, third, and fourth sensing signals, the reading circuit configured to process the first, second, third, and fourth sensing signals to output the first and second output signals.

8. The device of claim 7 wherein the reading circuit includes a combination stage configured to receive the first, second, third, and fourth sensing signals, the combination stage configured to output a first combination signal and a second combination signal.

9. The device of claim 8 wherein the reading circuit includes a first processing module and a second processing module, the first processing module configured to output the first output signal and the second processing module is configured to output the second output signal.

10. The device of claim 5, further comprising a driving assembly within the frame, the driving assembly including a first set of driving electrode and a second set of driving electrodes, the first pair and the second pair of sensing electrodes being between the first and second set of driving electrodes.

11. The device of claim 5, further comprising a first substrate and a second substrate, the frame being on the first substrate and the reading circuit being on the second substrate.

12. The device of claim 11 wherein the first side of the frame includes a plurality of contacts that couple the first pair and second pair of sensing electrodes to the reading circuit.

13. A device, comprising:

a reading circuit for a MEMS gyroscope, the reading circuit including;

an input stage being configured to receive a first pair of sensing signals from a first pair of sensing electrodes and a second pair of sensing signals from a second pair of sensing electrodes, each of the signals of the first pair of sensing signals and the second pair of sensing signals including components associated with rotations of the gyroscope around a first axis and a second axis; and

an output stage coupled to the input stage, the output stage being configured to output a first output signal associated with rotations about the first axis and a second output signal associated with rotations about the second axis, the reading circuit being configured to receive timing signals to turn off in pairs one of the sensing electrodes from the first pair and one of the sensing electrodes from the second pair.

14. The device of claim 13 wherein the input stage is configured to combine the components associated with rotations of the gyroscope around the first axis from each of the first pair and second pair of sensing signals to generate a first combination signal and to combine the components associated with rotations of the gyroscope around the second axis from each of the first pair and second pair of sensing signals to generate a second combination signal.

15. The device of claim 14 wherein the reading circuit includes a measurement stage configured to receive the first combination signal and the second combination signal, the measurement stage including a charge amplifier and a demodulator.

16. The device of claim 14 wherein the output stage includes a first axis processing stage that is configured to output the first output signal and a second axis processing stage that is configured to output the second output signal.

17. The device of claim 16 wherein the first axis processing stage includes a first sampling stage and a first filter stage, the second axis processing stage includes a second sampling stage and a second filter stage.