Method and system for quadrature error compensation

• US 9,052,335 B2
• Filed: 05/25/2012
• Issued: 06/09/2015
• Est. Priority Date: 05/26/2011
• Status: Active Grant

• Current Assignee: Maxim Integrated Products, Inc. (Analog Devices, Inc.)
• Original Assignee: Maxim Integrated Products, Inc. (Analog Devices, Inc.)
• Inventors: Coronato, Luca, Cazzaniga, Gabriele, Caminada, Carlo, Santoro, Manuel, Kondylis, Demetre, Prandi, Luciano
• Primary Examiner(s): Macchiarolo, Peter
• Assistant Examiner(s): KERAMET-AMIRCOLA, MOHAMMED E
• Application Number:
  US13/481,391
• Publication Number:
  US 20130133396A1
• Time in Patent Office: 1,110 Days
• Field of Search: 735/041.4, 73/13.8
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 7/02 containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS] B81B7/04 takes precedence
• 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 25/005 initial alignment, calibration or starting-up of inertial devices
• CPC Class Codes: G01P 21/00 Testing or calibrating of apparatus or devices covered by the preceding groups

Abstract

Disclosed are a MEMS sensor and methods to compensate a quadrature error on the sensor. The sensor detects movements of a substrate, especially accelerations and rotation rates. At least one mass arranged on the substrate and mounted to move relative to it is driven by drive electrodes. The mass executes a movement deviating from the prescribed movement due to a quadrature error. A deflection of the mass occurring due to Coriolis force and quadrature error is detected with detection electrodes. A capacitance change is detected as a function of drive movement of the mass by using compensation electrodes. A compensation charge dependent on the quadrature error of the MEMS sensor is generated on the compensation electrodes. For compensation, the distorted or incorrect charge generated by the quadrature error in the detection electrodes is compensated with the compensation charge.

Claims

1. A method for compensation of a quadrature error on an MEMS sensor, the method comprising:

reading out a drive movement using detection electrodes;

detecting a movement of at least one mass arranged on a substrate and mounted to move relative to drive electrodes, the movement deviating from a prescribed movement due to a quadrature error;

identifying a capacitance change as a function of drive movement of the at least one mass using a plurality of compensation electrodes;

generating a compensation charge on the compensation electrodes, the compensation charge being dependent on the quadrature error; and

wherein the quadrature error in the detection electrodes is compensated using the compensation charge without changing a deviating movement of the mass caused by the quadrature error.

2. The method of claim 1 wherein the capacitance change generated by the quadrature error and the compensation charge essentially cancel each other out.

3. The method of claim 1 wherein a predetermined voltage dependent on the quadrature error is applied to the compensation electrodes to generate the compensation charge.

4. The method of claim 1 wherein the compensation charge and the capacitance change of the detection electrodes are superimposed one on the other.

5. The method of claim 4 wherein a result from superimposing the capacitance change and the compensation charge is provided to evaluation electronics.

6. The method of claim 1 wherein the compensation charge and the capacitance change are provided to evaluation electronics.

7. The method of claim 1 wherein the compensation charge is regulated as a function of quadrature error.

8. The method of claim 1 wherein the quadrature error of the MEMS sensor or a voltage dependent on the quadrature error are determined after production of the MEMS sensor.

9. The method of claim 1 wherein the quadrature error of the MEMS sensor or a voltage dependent on the quadrature error are determined during operation of the MEMS sensor.

10. A MEMS sensor for detection of movements of a substrate the sensor comprising:

a substrate;

at least one mass arranged on the substrate and mounted to move relative to a movement of the substrate and driven by drive electrodes;

at least one detection electrode arranged on the substrate, the at least one detection electrode detecting a deflection of the at least one mass due to a Coriolis force and a quadrature error;

at least one compensation electrode arranged on the substrate to record a capacitance change as a function of a drive movement of the at least one mass; and

a voltage source, which applies a predetermined voltage dependent on the quadrature error to the at least one compensation electrode to generate a compensation charge that is used to compensate for at least a portion of the quadrature error.

11. The sensor of claim 10 wherein an evaluation device uses the compensation charge to compensate for the at least portion of the quadrature error.

12. The sensor of claim 10 wherein the MEMS sensor is a one- or multidimensional sensor.

13. The sensor of claim 10 further comprising a compensation electrode device to detect and evaluate a drive movement and/or to drive the at least one mass.