Magneto-resistive sensor for measuring a magnetic field based on an anisotropic magneto-resistive (AMR) effect or a gigantic magneto-resistive (GMR) effect
Magnetoresistive sensors based on the AMR or GMR effect exhibit substantially enlarged linear characteristic curve regions as a result of the fact that their resistances are composed of magnetoresistive layer strips of differing anisotropic forms. Differing anisotropic forms can be achieved by different strip widths, strip thicknesses, strip intervals or strip materials. The temperature compensation for the output voltage of the magnetoresistive sensors, at least at one point on the characteristic curve, is achieved by the series connection of an additional layer strip with a temperature coefficient that differs from that of the magnetoresistive material to at least one magnetoresistive resistance of the sensor.
1. A magneto-resistive sensor for measuring a magnetic field based on an anisotropic magneto-resistive (AMR) effect or a gigantic magneto-resistive (GMR) effect, comprising:
a substrate;
a plurality of resistors formed from magneto-resistive layer strips and arranged in form of a half or full bridge circuit on the substrate, said plurality of resistors having a resistance value that depends on a magnetic field strength,
wherein at least one of the plurality of resistors includes a magneto-resistive layer strip with a shape anisotropy different from a shape anisotropy of another magneto-resistive layer strip for increasing a linear region on a characteristic curve describing a dependence of the resistance of a sensor on the magnetic field strength, the shape anisotropy being caused by differences in width of the magneto-resistive layer strips, the magneto-resistive layer strips having a same shape.
2. The magneto-resistive sensor of claim 1 , wherein at least one of the magneto-resistive layer strips of a resistor has a thickness different from another one of the magneto-resistive layer strips.
3. The magneto-resistive sensor of claim 1 , wherein at least one of the magneto-resistive layer strips is made of a material different from another one of the magneto-resistive layer strips.
4. The magneto-resistive sensor of claim 1 , wherein a spacing between the magneto-resistive layer strips of a resistor is not uniform.
5. The magneto-resistive sensor of claim 1 wherein the magneto-resistive layer strips include sublayers, and wherein a coupling field strength between the sublayers of the magneto-resistive layer strips is different.
6. The magneto-resistive sensor of claim 1 , wherein each of the resistors comprises a plurality of magneto-resistive layer strips which are connected in series and have a parallel longitudinal direction.
7. The magneto-resistive sensor of claim 6 , wherein the resistors are formed of layer strips exhibiting the AMR effect and the longitudinal directions of the layer strips of the two resistors of the half bridge circuit form a right angle.
8. The magneto-resistive sensor of claim 7 , wherein the plurality of resistors form a full-bridge circuit and the longitudinal directions of the layer strips of the resistors which are diagonally opposed in the full bridge circuit are parallel to each other.
9. The magneto-resistive sensor of claim 8 , wherein two diagonally opposed resistors of the full bridge circuit have layer strips of different widths with a parallel longitudinal direction.
10. The magneto-resistive sensor of claim 9 , wherein a direction of the magnetic field to be measured is essentially perpendicular to the longitudinal direction of the layer strips of different widths.
11. The magneto-resistive sensor of claim 9 , wherein a constant magnetic auxiliary field is applied in the longitudinal direction of the layer strips of different widths.
12. The magneto-resistive sensor of claim 1 , wherein the plurality of resistors comprise two resistors forming a half-bridge circuit and the two resistors of the half bridge circuit are formed of GMR layer strips and wherein a direction of a remanent magnetization in the two resistors of the half bridge circuit is different.
13. The magneto-resistive sensor of claim 1 , wherein the plurality of resistors form a full-bridge circuit and are formed of layer strips exhibiting the GMR effect and directions of the magnetization of the GMR layer strips of the resistors which are diagonally opposed in the full bridge circuit are parallel to each other.
14. The magneto-resistive sensor of claim 13 , wherein the directions of the magnetization of the GMR layer strips are parallel to a longitudinal direction of the strips.
15. The magneto-resistive sensor of claim 1 , wherein at least one of the plurality of resistors comprises at least one trim layer region with an adjustable resistance value.
16. The magneto-resistive sensor of claim 15 , wherein a material of the at least one trim layer region is the same as a material of the magneto-resistive layer strips.