Sensor And Method For Sensing The Linear Acceleration And An Angular Velocity

• US 20080202237A1
• Filed: 02/28/2007
• Published: 08/28/2008
• Est. Priority Date: 02/28/2007
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Hammerschmidt, Dirk
• Granted Patent: US 7,950,281 B2
• Time in Patent Office: Days
• US Class Current: 73/504.04
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01P 15/097 by vibratory elements
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions

Abstract

A sensor has a suspended mechanical resonator being responsive to one of a linear acceleration and an angular velocity of the sensor such that a first area and a second area are subjected to opposite elongation movements and responsive to the other such that the first area and the second area are subjected to a common elongation movement, a first mechanical-electrical interface interacting with the first area, a second mechanical-electrical interface interacting with the second area, a common mode signal generator coupled to the mechanical-electrical interfaces with a common mode signal output, a differential mode signal generator coupled to the mechanical-electrical interfaces with a differential mode signal output, a first processing circuit coupled to the differential mode output, with an output for a first processed signal, and a second processing circuit coupled to the common mode output with an output for a second processed signal.

Claims

1. A sensor comprising:

a suspended mechanical resonator capable of oscillating in at least an excitation mode and comprising a first area and a second area, the suspended mechanical resonator being responsive to one of a linear acceleration of the sensor and an angular velocity of the sensor such that the first area and the second area are subjected to opposite elongation movements along an elongation direction, and being responsive to the other of the linear acceleration of the sensor and the angular velocity of the sensor such that the first area and the second area are subjected to a common elongation movement along the elongation direction;

a first mechanical-electrical interface interacting with the first area with a terminal, at which a first elongation signal indicative of the elongation of the first area is obtainable;

a second mechanical-electrical interface interacting with the second area with a terminal, at which a second elongation signal indicative of the elongation of the second area is obtainable;

a common mode signal generator coupled to the first mechanical-electrical interface and the second mechanical-electrical interface with a common mode signal output for a common mode signal based upon the first and the second elongation signals;

a differential mode signal generator coupled to the first mechanical-electrical interface and the second mechanical-electrical interface with a differential mode signal output for a differential mode signal based upon the first and the second elongation signal;

a first processing circuit coupled to the differential mode output, with an output for a first processed signal based upon the differential mode signal, indicative of the one of the linear acceleration of the sensor and the angular velocity of the sensor; and

a second processing circuit coupled to the common mode output with an output for a second processed signal based upon the common mode signal, indicative of the other of the linear acceleration of the sensor and the angular velocity of the sensor.

2. The sensor according to claim 1, wherein the one of the linear acceleration of the sensor and the angular velocity of the sensor is the angular velocity of the sensor and wherein the other of the linear acceleration of the sensor and the angular velocity of the sensor is the linear acceleration.

3. The sensor according to claim 1, further comprising a first analog/digital converter coupled in between the terminal of the first mechanical-electrical interface, the terminal of the second mechanical-electrical interface and the common mode signal generator and the differential mode signal generator, such that the common mode signal generator and the differential mode signal generator are capable of digitally processing the first and second elongation signals.

4. The sensor according to claim 1, wherein the interaction between the first mechanical-electrical interface and the first area and the second mechanical-electrical interface and the second area is an electrostatic/capacitive or a magnetic/inductive interaction.

5. The sensor according to claim 1, wherein the first mechanical-electrical interface comprises a first detection electrode electrostatically/capacitively coupled to the first area and wherein the second mechanical-electrical interface comprises a second detection electrode electrostatically/capacitively coupled to the second area.

6. The sensor according to claim 5, wherein the sensor further comprises an additional driver connected to the suspended mechanical resonator and able of providing a common potential to the suspended mechanical resonator.

7. The sensor according to claim 1, further comprising an exciter with an exciter mechanical-electrical interface capable of influencing a first excitation area and a second excitation area of the suspended mechanical resonator.

8. The sensor according to claim 7, wherein the exciter and the exciting mechanical-electrical interface operates in a closed feedback loop such that the excitation mode is a resonance mode of the suspended mechanical resonator.

9. The sensor according to claim 7, wherein the excitation mechanical-electrical interface comprises a first excitation electrode electrostatically/capacitively coupled to the first excitation area and a second excitation electrode electrostatically/capacitively coupled to the second excitation area, and wherein the exciter is capable of providing an excitation signal to the first excitation electrode and the second excitation electrode comprising a differential component such that the excitation mode of the suspended mechanical resonator is based on the differential component of the excitation signal.

10. The sensor according to claim 9, wherein the exciter further comprises a digital/analog converter and an analog/digital converter such that the closed feedback loop is based on a digital signal processing.

11. The sensor according to claim 9, wherein the exciter is further capable of providing a common component of the excitation signal to the first excitation electrode and the second excitation electrode such that the properties of the excitation mode are alterable.

12. The sensor according to claim 1, further comprising a differential mode feedback controller coupled to a different mode signal output with an output for a differential feedback signal, a common mode feedback controller coupled to the common mode signal output with an output for a feedback common mode signal and a signal generator coupled to the common mode feedback controller and the differential mode feedback controller with an output for a first feedback signal and an output for a second feedback signal, wherein the first and the second feedback signals are based on the common mode feedback signal and the differential mode feedback signal, and wherein the output for the first feedback signal is coupled to the first mechanical/electrical interface and the output for the second feedback signal is coupled to the second mechanical-electrical interface such that the elongation of the first area and the elongation of the second area are compensable.

13. The sensor according to claim 12, wherein the first mechanical-electrical interface and the second mechanical-electrical interface comprise a multiplexer such that the first elongation signal and the second elongation signal are providable to the common mode signal generator and the differential mode signal generator without being influenced by the first feedback signal and the second feedback signal.

14. The sensor according to claim 12, wherein the signal generator comprises a digital/analog converter such that the differential mode feedback controller and the common mode feedback controller are capable of a digital signal processing.

15. The sensor according to claim 1, wherein the suspended mechanical resonator is a MEMS mechanical resonator.

16. A sensor comprising:

a suspended mechanical resonator capable of oscillating in at least an excitation mode and comprising a first area, a second area, a first excitation area and a second excitation area, the suspended mechanical resonator being responsive to an angular velocity of the sensor such that the first area and the second area are subjected to opposite elongation movements along an elongation direction and being responsive to a linear acceleration of the sensor such that the first area and the second area are subjected to common elongation movement along the elongation direction;

a first detection electrode interacting with the first area with a terminal, at which a first elongation signal indicative of the elongation of the first area is obtainable;

a second detection electrode interacting with the second area with a terminal, at which a second elongation signal indicative of the elongation of the second area is obtainable;

a first excitation electrode interacting with the first excitation area with a terminal for a first excitation signal;

a second excitation electrode interacting with the second excitation area with a terminal for a second excitation signal;

a common mode signal generator coupled to the first detection electrode and the second detection electrode with a common mode signal output for a common mode signal based upon the first and the second elongation signals;

a differential mode signal generator coupled to the first detection electrode and the second detection electrode with a differential mode signal output for a differential mode signal based upon the first and second elongation signals;

a first processing circuit coupled to the differential mode output with an output for a first process signal based upon the differential mode signal indicative of the angular velocity of the sensor;

a second processing circuit coupled to the common mode output with an output for a second process signal based upon the common mode signal indicative of the linear acceleration of the sensor; and

an exciter coupled to the first excitation electrode and the second excitation electrode such that the exciter is capable of exciting the suspended mechanical resonator to oscillate in the excitation mode.

17. The sensor according to claim 16, wherein the suspended mechanical resonator is a MEMS mechanical resonator.

18. The sensor according to claim 16, wherein the exciter is coupled to the first excitation electrode and the second excitation electrode such that the suspended mechanical resonator is excited in a closed feedback loop, so that the excitation mode is a resonance mode of the suspended mechanical resonator.

19. The sensor according to claim 18, wherein the exciter comprises an analog/digital converter and the digital/analog converter such that the closed feedback loop is based on a digital signal processing.

20. The sensor according to claim 16, further comprising an analog/digital converter coupled in between the first detection electrode, the second detection electrode and the common mode signal generator and the differential mode signal generator such that the common mode signal generator and the differential mode signal generator are capable of digitally processing the first and the second elongation signals.

21. The sensor according to claim 16, further comprising a differential mode feedback controller coupled to the differential mode signal output with an output for a differential mode feedback signal based on the differential mode signal, a common mode feedback controller coupled to the common mode signal output with an output for a common mode feedback signal based upon the common mode signal, and a signal generator coupled to the output of the differential mode feedback controller for the differential mode feedback signal and the output of the common mode feedback controller for the common mode feedback signal with an output for a first feedback signal based upon the common mode feedback signal and the differential mode feedback signal and an output for a second feedback signal based upon the common mode feedback signal and the differential mode feedback signal, wherein the output for the first feedback signal is coupled to the first detection electrode and wherein the output for the second feedback signal is coupled to the second detection electrode such that the elongation of the first and the second area are compensable.

22. The sensor according to claim 21, further comprising a multiplexer coupled in between the first detection electrode, the second detection electrode, the common mode signal generator and the differential mode signal generator and connected to the output of the signal generator such that the first feedback signal and the second feedback signal are able of being provided to the first detection electrode and the second detection electrode, respectively, without disturbing the first elongation signal and the second elongation signal, respectively.

23. The sensor according to claim 21, wherein the signal generator comprises a digital/analog converter such that the common mode feedback generator and the differential mode feedback generator are capable of digitally processing signals.

24. A sensing means comprising:

a means for oscillating in at least an excitation mode comprising a first area and a second area, the means for oscillating being responsive to one of a linear acceleration of the sensing means and an angular velocity of the sensing means such that the first area and the second area are subjected to opposite elongation movements along an elongation direction, and being responsive to the other of the linear acceleration of the sensing means and the angular velocity of the sensing means such that the first area and the second area are subjected to a common elongation movement along the elongation direction;

a first mechanical-electrical means for interacting with a first area and for detecting the elongation of the first area;

a second mechanical-electrical means for interacting with a second area and for detecting the elongation of the second area;

a means for providing a common mode signal based on the elongation of the first area and the elongation of the second area;

a means for providing a differential mode signal based upon the elongation of the first area and the elongation of the second area;

a means for processing the differential mode signal and for providing a first processed signal based upon the differential mode signal indicative of the one of the linear acceleration of the sensor and the angular velocity of the sensor; and

a means for processing the common mode signal and for providing a second processed signal based upon the common mode signal indicative of the other of the linear acceleration of the sensor and the angular velocity of the sensor.

25. A method for sensing a linear acceleration and an angular velocity with a suspended mechanical resonator capable of oscillating in at least an excitation mode comprising a first area and a second area, the suspended mechanical resonator being responsive to one of a linear acceleration of a sensor and an angular velocity of the sensor such that the first area and the second area are subjected to opposite elongation movements along an elongation direction, and being responsive to the other of the linear acceleration of the sensor and the angular velocity of the sensor such that the first area and the second area are subjected to a common elongation movement along the elongation direction, comprising:

detecting the elongation of the first area;

detecting the elongation of the second area;

generating a common mode signal based upon the elongation of the first area and the elongation of the second area;

generating a differential mode signal based upon the elongation of the first area and the elongation of the second area;

processing the differential mode signal to a first processed signal indicative of the one of the linear acceleration of the sensor and the angular velocity of the sensor; and

processing the common mode signal to a second processed signal indicative of the other of the linear acceleration of the sensor and the angular velocity of the sensor.

26. A method for detecting the linear acceleration and an angular velocity with a suspended mechanical resonator capable of oscillating in at least an excitation mode and comprising a first area, a second area, a first excitation area and a second excitation area, the suspended mechanical resonator being responsive to the angular velocity of a sensor such that the first area and the second area is subjected to opposite elongation movements along the elongation direction, being responsive to the linear acceleration of the sensor such that the first area and the second area are subjected to a common elongation movement along the elongation direction, and being responsive to oscillating in the excitation mode upon an interaction with a first excitation area and a second excitation area, comprising:

interacting with the first excitation area and the second excitation area to excite the excitation mode of the suspended mechanical resonator;

detecting the elongation of the first area;

detecting the elongation of the second area;

generating a common mode signal based upon the elongation of the first area and the elongation of the second area;

generating a differential mode signal based upon the elongation of the first area and the elongation of the second area;

processing the differential mode signal to a first processed signal indicative of the angular velocity of the sensor; and

processing the common mode signal to a second processed signal indicative of the linear acceleration of the sensor.

27. A computer program product comprising code stored on a computer readable medium, said code when running on a computer, performing a method for sensing the linear acceleration and an angular velocity with a suspended mechanical resonator capable of oscillating in at least an excitation mode and comprising a first area and a second area, the suspended mechanical resonator being responsive to one of a linear acceleration of a sensor and an angular velocity of the sensor such that the first area and the second area are subjected to opposite elongation movements along an elongation direction, and being responsive to the other of the linear acceleration of the sensor and the angular velocity of the sensor such that the first area and the second area are subjected to a common elongation movement along the elongation direction, comprising:

detecting the elongation of the first area;

detecting the elongation of the second area;

generating a common mode signal based upon the elongation of the first area and the elongation of the second area;

generating a differential mode signal based upon the elongation of the first area and the elongation of the second area;

processing the differential mode signal to a first processed signal indicative of the one of the linear acceleration of the sensor and the angular velocity of the sensor; and

processing the common mode signal to a second processed signal indicative of the other of the linear acceleration of the sensor and the angular velocity of the sensor.

28. A computer program product comprising code stored on a computer readable medium, said code when running on a computer, performing a method for detecting the linear acceleration and an angular velocity comprising a suspended mechanical resonator capable of oscillating in at least an excitation mode and comprising a first area, a second area, a first excitation area and a second excitation area, the suspended mechanical resonator being responsive to the angular velocity of a sensor such that the first area and the second area is subjected to opposite elongation movements along the elongation direction, being responsive to the linear acceleration of the sensor such that the first area and the second area are subjected to a common elongation movement along the elongation direction, and being responsive to oscillating in the excitation mode upon an interaction with a first excitation area and a second excitation area, comprising:

interacting with the first excitation area and the second excitation area to excite the excitation mode of the suspended mechanical resonator;

detecting the elongation of the first area;

detecting the elongation of the second area;

generating a common mode signal based upon the elongation of the first area and the elongation of the second area;

generating a differential mode signal based upon the elongation of the first area and the elongation of the second area;

processing the differential mode signal to a first processed signal indicative of the angular velocity of the sensor; and

processing the common mode signal to a second processed signal indicative of the linear acceleration of the sensor.