Dual axis magnetic sensor
First Claim
1. A magnetic field sensing device comprising:
- a first sensor and a second sensor formed in a common plane on a single semiconductor substrate;
said first sensor having a first bridge arrangement comprising GMR material formed on said substrate, said GMR material having a free layer having a crystal anisotropy field and having an easy axis of effective anisotropy field in a first direction, said first sensor being sensitive to first magnetic field components perpendicular to said first direction;
means for producing a current flow through said first sensor and sensing variations in the resistivity of said first sensor due to said first magnetic field components with an output of said first bridge arrangement representing said first magnetic field components;
said second sensor having a second bridge arrangement comprising said GMR material formed on said substrate, said GMR material having a free layer having said crystal anisotropy field and having an easy axis of effective anisotropy field in a second direction substantially perpendicular to said first direction, said second sensor being sensitive to second magnetic field components perpendicular to a sensitive direction of said first sensor, means for producing a current flow through said second sensor and sensing variations in the resistivity of said second sensor due to said second magnetic field components with an output of said second bridge arrangement representing said second magnetic field components.
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Accused Products
Abstract
A two-axis magnetic field sensor includes a substrate, a first sensor having at least one magnetoresistive element formed of GMR material on the substrate has a free layer having an easy axis of effective anisotropy field in a first direction. The first sensor is sensitive to magnetic field components perpendicular to the first direction. A current is caused to flow through the first sensor and variations in the resistivity of the first sensor due to the first magnetic field components are sensed. A second sensor having at least one magnetoresistive element formed of GMR material on the substrate has a free layer having an easy axis of effective anisotropy field in a direction substantially perpendicular to the first direction. The second sensor is sensitive to second magnetic field components perpendicular to its easy axis of effective anisotropy. A current is caused to flow through the second sensor and variations in the resistivity of the second sensor due to second magnetic field components are sensed.
169 Citations
20 Claims
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1. A magnetic field sensing device comprising:
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a first sensor and a second sensor formed in a common plane on a single semiconductor substrate;
said first sensor having a first bridge arrangement comprising GMR material formed on said substrate, said GMR material having a free layer having a crystal anisotropy field and having an easy axis of effective anisotropy field in a first direction, said first sensor being sensitive to first magnetic field components perpendicular to said first direction;
means for producing a current flow through said first sensor and sensing variations in the resistivity of said first sensor due to said first magnetic field components with an output of said first bridge arrangement representing said first magnetic field components;
said second sensor having a second bridge arrangement comprising said GMR material formed on said substrate, said GMR material having a free layer having said crystal anisotropy field and having an easy axis of effective anisotropy field in a second direction substantially perpendicular to said first direction, said second sensor being sensitive to second magnetic field components perpendicular to a sensitive direction of said first sensor, means for producing a current flow through said second sensor and sensing variations in the resistivity of said second sensor due to said second magnetic field components with an output of said second bridge arrangement representing said second magnetic field components. - View Dependent Claims (2, 3, 4, 5, 6, 17, 18, 19, 20)
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7. A magnetic field sensing device comprising:
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a first sensor and a second sensor formed in a common plane on a single semiconductor substrate;
said first sensor formed on said substrate and comprising at least one magnetoresistive element having a first and a second thin film layer of ferromagnetic material separated by a thin film layer of non-magnetic material with said second thin film layer of ferromagnetic material having a crystal anisotropy field and having an easy axis of effective anisotropy field in a first direction, with said first thin film layer having a direction of magnetization and said second thin film layer having a direction of magnetization at zero applied field;
means for producing a current flow through said magnetoresistive element of said first sensor;
means for sensing variations in the resistivity of said magnetoresistive element of said first sensor due to the difference in rotation of said magnetization in said first and said second layers as a function of first magnetic field components being sensed;
said second sensor formed on said substrate and comprising at least one magnetoresistive element having a first and a second thin film layer of ferromagnetic material separated by a thin film layer of non-magnetic material with said second thin film layer of ferromagnetic material having said crystal anisotropy field and having an easy axis of effective anisotropy field in a direction substantially perpendicular to said first direction, with said first thin film layer having a direction of magnetization and said second thin film layer having a direction of magnetization at zero applied field;
means for producing a current flow through said magnetoresistive element of said second sensor; and
means for sensing variations in the resistivity of said magnetoresistive element of said second sensor due to the difference in rotation of said magnetization in said first and said second layers as a function of second magnetic field components being sensed wherein said second magnetic field components are perpendicular to said first magnetic field components. - View Dependent Claims (8, 9, 10, 11)
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12. A magnetic field sensing device comprising:
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a first sensor and a second sensor formed in a common plane on a single semiconductor substrate;
said first sensor comprising first, second, third and fourth magnetoresistive elements formed on said substrate and connected in a bridge arrangement having a first output, each of said magnetoresistive elements having a free magnetic layer having a crystal anisotropy field and having an easy axis of effective anisotropy field oriented in a first direction at zero applied magnetic field, a pinned magnetic layer, a spacer of non magnetic material between said free layer and said pinned layer, and a layer of antiferromagnetic material adjacent said pinned layer and pinning said pinned layer in a direction generally perpendicular to said easy axis of effective anisotropy field;
said second sensor comprising fifth, sixth, seventh and eighth magnetoresistive elements formed on said substrate and connected in a bridge arrangement having a second output, each said magnetoresistive elements having a free magnetic layer having said crystal anisotropy field and having an easy axis of effective anisotropy field substantially perpendicular to said first direction at zero applied magnetic field, a pinned ferromagnetic layer, a spacer of non magnetic material between said free layer and said pinned layer and a layer of antiferromagnetic material adjacent said pinned layer and pinning said pinned layer in a direction generally perpendicular to said easy axis of effective anisotropy field;
means for setting a direction of magnetization of said pinned layer of said magnetoresistive elements of said first sensor and of said second sensor so that a first pair of diagonally opposite bridge elements are pinned in one direction and a remaining pair of diagonally opposite bridge elements are pinned in a direction opposite said one direction; and
wherein said first output is representative of first magnetic field components at said first sensor and substantially perpendicular to said first direction and said second output is representative of second magnetic field components at said second sensor and substantially perpendicular to said first magnetic field components. - View Dependent Claims (13, 14, 15, 16)
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Specification