Minimum magnetic field detection systems and methods in magnetoresistive sensors

Patent metadata

Field	Value
Publication number	US-9316706-B2
Application number	US-201213493412-A
Country	US
Kind code	B2
Filing date	Jun 11, 2012
Priority date	Jun 11, 2012
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

Embodiments relate to magnetoresistive sensors suitable for both angle and field strength sensing. A sensor can comprise two magnetoresistive (xMR) sensor components for sensing two different aspects/characteristics of a magnetic field. The first xMR sensor component can be configured for magnetic field angle or rotation sensing, while the second xMR sensor component is configured for magnetic field strength sensing. The second xMR sensor component can be configured for magnetic field strength sensing in two dimensions. In an embodiment, the second xMR sensor can be sensitive to lower magnetic fields, while the first xMR sensor can be sensitive to relatively higher magnetic fields. In an exemplary operation, the second xMR sensor can determine whether the field sensed with respect to angle or rotation by the first xMR sensor component is of sufficient strength to increase the accuracy of the angle or rotation of the field sensed by the first xMR sensor.

First claim

What is claimed is:

1. A magnetoresistive (xMR) sensor comprising:
xMR magnetic field angle sensing circuitry configured to determine a magnetic field angle of a magnetic field; and
xMR magnetic field magnitude sensing circuitry arranged in a sensor package with the xMR magnetic field angle sensing circuitry, the xMR magnetic field magnitude sensing circuitry being configured to:
determine a magnetic field strength of the magnetic field; and
determine an accuracy of the magnetic field angle determined by the xMR magnetic field angle sensing circuitry based on the magnetic field strength.

2. The xMR sensor of claim 1 , wherein the xMR sensor comprises at least one of a giant magnetoresistive (GMR) sensor, a tunneling magnetoresistive (TMR) sensor or an anisotropic magnetoresistive sensor (AMR).

3. The xMR sensor of claim 1 , wherein the xMR magnetic field angle sensing circuitry and the xMR magnetic field magnitude sensing circuitry each comprise a Wheatstone bridge configuration.

4. The xMR sensor of claim 1 , wherein a width of xMR sensing elements of the xMR magnetic field magnitude sensing circuitry is less than a width of xMR sensing elements of the xMR magnetic field angle sensing circuitry.

5. The xMR sensor of claim 1 , wherein the xMR magnetic field angle sensing circuitry and the xMR magnetic field magnitude sensing circuitry are arranged on a substrate.

6. The xMR sensor of claim 1 , wherein the xMR magnetic field angle sensing circuitry and the xMR magnetic field magnitude sensing circuitry are produced in a same production step.

7. The GMR sensor of claim 1 , wherein a magnetization reference of the xMR magnetic field angle sensing circuitry and a magnetization reference of the xMR magnetic field magnitude sensing circuitry are magnetized in a same production step.

8. The xMR sensor of claim 7 , wherein the xMR magnetic field angle sensing circuitry and the xMR magnetic field magnitude sensing circuitry are magnetized by a high-temperature anneal process.

9. The xMR sensor of claim 1 , further comprising a first multiplexer, a second multiplexer, and an analog-to-digital converter (ADC), the first and second multiplexers being coupled to the xMR magnetic field angle sensing circuitry and the xMR magnetic field magnitude sensing circuitry, respectively, and the ADC being coupled to respective outputs of the first and second multiplexers.

10. The xMR sensor of claim 1 , further comprising:
an analog-to-digital converter (ADC) coupled to the xMR magnetic field angle sensing circuitry; and
a multiplexer coupled to the xMR magnetic field magnitude sensing circuitry and to a temperature sensor.

11. The xMR sensor of claim 10 , further comprising a temperature analog-to-digital converter (ADC) coupled to an output of the multiplexer.

12. The xMR sensor of claim 1 , wherein the xMR magnetic field magnitude sensing circuitry is configured to calculate a vector length from a first bridge voltage and a second bridge voltage of the xMR magnetic field magnitude sensing circuitry to determine the magnetic field strength of the magnetic field.

13. The xMR sensor of claim 12 , wherein the xMR magnetic field magnitude sensing circuitry is configured to compare the vector length to a magnetic field strength threshold value.

14. The xMR sensor of claim 13 , wherein the xMR magnetic field magnitude sensing circuitry is configured to determine the accuracy of the magnetic field angle based on the comparison.

15. The xMR sensor of claim 1 , wherein the xMR magnetic field magnitude sensing circuitry is further configured to compare the magnetic field strength to a magnetic field strength threshold value, wherein the determining of the accuracy of the magnetic field angle is based on the comparison.

16. The xMR sensor of claim 15 , wherein the determining the accuracy of the magnetic field angle comprises:
determining a first accuracy when the magnetic field strength is greater than the magnetic field strength threshold value; and
determining a second accuracy when the magnetic field strength is less than the magnetic field strength threshold value.

17. The xMR sensor of claim 15 , wherein the determining the accuracy of the magnetic field angle comprises:
identifying the magnetic field angle as accurate when the magnetic field strength is greater than the magnetic field strength threshold value; and
identifying the magnetic field angle as inaccurate when the magnetic field strength is less than the magnetic field strength threshold value.

18. The xMR sensor of claim 16 , wherein the first accuracy identifies the magnetic field angle as accurate and the second accuracy identifies the magnetic field angle as inaccurate.

Assignees

• Granig Wolfgang
• Zimmer Juergen
• Infineon Technologies Ag

Inventors

• Granig Wolfgang
• Zimmer Juergen

Classifications

• G01R33/093 Primary

  using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00) · CPC title

• G01R33/09 Primary

  Magnetoresistive devices · CPC title

• G01R33/0047

  Housings or packaging of magnetic sensors (packaging of semiconductor devices H10W99/00); Holders · CPC title

• G01R33/091 Primary

  Constructional adaptation of the sensor to specific applications · CPC title