Method of biasing a magneto resistive sensor element

• US 7,839,141 B2
• Filed: 08/14/2007
• Issued: 11/23/2010
• Est. Priority Date: 08/14/2007
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Werth, Tobias, Zimmer, Juergen
• Primary Examiner(s): LeDynh; Bot L
• Application Number:
  US11/838,569
• Publication Number:
  US 20090046398A1
• Time in Patent Office: 1,197 Days
• Field of Search: 324/207.21, 324/207.25, 324/252
• US Class Current: 324/207.21
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G01D 5/147 influenced by the movement of a third element, the position of Hall device and the source of magnetic field being fixed in respect to each other
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00

Abstract

A method of biasing a magneto resistive sensor element includes providing at least one magneto resistive sensor element having a magnetic sensitivity along a first axis that is parallel to a plane of the at least one sensor element. A magnet is positioned adjacent to the at least one sensor element for biasing the at least one sensor element, wherein the magnet has a magnetization that is non-perpendicular to the plane of the at least one sensor element, and wherein the magnetization includes a component parallel to the plane of the at least one sensor element that increases a sensitive range of the at least one sensor element along the first axis.

Claims

1. A method of biasing a magneto resistive sensor element, comprising:

providing at least one magneto resistive sensor element having a magnetic sensitivity along a first axis that is parallel to a plane of the at least one sensor element; and

positioning a magnet adjacent to the at least one sensor element for biasing the at least one sensor element, wherein the magnet has a magnetization that is non-perpendicular to the plane of the at least one sensor element, and wherein the magnetization includes a component parallel to the plane of the at least one sensor element that increases a sensitive range of the at least one sensor element along the first axis, wherein the component parallel to the plane of the at least one sensor element has a magnitude of greater than about 10 mT.

2. The method of claim 1, wherein the at least one magneto resistive sensor element comprises at least one GMR element.

3. The method of claim 1, wherein the at least one magneto resistive sensor element comprises a plurality of magneto resistive sensor elements configured to operate in a differential manner.

4. The method of claim 1, wherein the at least one magneto resistive sensor element comprises four GMR elements arranged in a bridge configuration.

5. The method of claim 4, wherein the four GMR elements arranged in a bridge configuration comprise a gradiometric sensor.

6. The method of claim 1, wherein the at least one magneto resistive sensor element is configured to measure position or speed of a magnetic gear wheel.

7. The method of claim 1, wherein the magnet is a cubic magnet.

8. The method of claim 1, wherein the magnet is a cylindrically-shaped magnet.

9. The method of claim 1, wherein the first axis is in an x-axis, wherein the magnet has a magnetization with a first component along a z-axis perpendicular to the plane of the at least one sensor element and with a second component along a y-axis parallel to the plane of the sensor element, wherein the x, y, and z axes are orthogonal axes, and wherein the second component increases the sensitive range of the at least one sensor element along the x-axis.

10. The method of claim 9, wherein the second component has a magnitude of greater than about 20 mT.

11. The method of claim 9, wherein the second component has a magnitude of greater than about 40 mT.

12. A magneto resistive sensor, comprising:

at least one magneto resistive sensor element having a magnetic sensitivity in an x-axis that is parallel to a plane of the at least one sensor element; and

a back bias magnet configured to bias the at least one sensor element with a magnetic field having a first component along a z-axis perpendicular to the plane of the at least one sensor element, and having a second component along a y-axis parallel to the plane of the at least one sensor element, wherein the x, y, and z axes are orthogonal axes, and wherein the second component increases a sensitive range of the at least one sensor element along the x-axis, and wherein the second component has a magnitude of greater than about 10 mT.

13. The sensor of claim 12, wherein the at least one magneto resistive sensor element comprises at least one GMR element.

14. The sensor of claim 12, wherein the at least one magneto resistive sensor element comprises a plurality of magneto resistive sensor elements configured to operate in a differential manner.

15. The sensor of claim 12, wherein the at least one magneto resistive sensor element comprises four GMR elements arranged in a bridge configuration.

16. The sensor of claim 12, wherein the magneto resistive sensor is configured as a gradiometric sensor.

17. The sensor of claim 12, wherein the at least one magneto resistive sensor element is configured to measure position or speed of a magnetic gear wheel.

18. The sensor of claim 12, wherein the magnet is a cubic magnet.

19. The sensor of claim 12, wherein the magnet is a cylindrically-shaped magnet.

20. The sensor of claim 12, wherein the second component has a magnitude of greater than about 20 mT.

21. The sensor of claim 12, wherein the second component has a magnitude of greater than about 40 mT.

22. A GMR sensor, comprising:

a sensor element having a plurality of GMR elements, each GMR element having a magnetic sensitivity in an x-axis that is parallel to a plane of the sensor element; and

a magnet configured to bias the sensor element with a magnetic field having a first component along a z-axis perpendicular to the plane of the sensor element, and having a second component along a y-axis parallel to the plane of the sensor element, wherein the x, y, and z axes are orthogonal axes, and wherein the second component has a magnitude of greater than about 10 mT.