Magnetic field sensor for sensing a movement of a ferromagnetic target object
First Claim
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1. A magnetic field sensor for sensing a movement of a ferromagnetic target object having ferromagnetic target object features with a target feature width, comprising:
- a substrate;
a first full bridge circuit disposed upon the substrate and proximate to the ferromagnetic target object, comprising;
a first magnetoresistance element;
a second magnetoresistance element, the first and second magnetoresistance elements proximate to each other forming a first proximate pair;
a third magnetoresistance;
a fourth magnetoresistance element, the third and fourth magnetoresistance elements proximate to each other forming a second proximate pair;
a first noninverting output node joining a selected two of the first, second, third and fourth magnetoresistance elements;
a first inverting output node joining a different selected two of the first, second, third and fourth magnetoresistance elements, wherein a first differential signal is generated between the first noninverting node and the first inverting node, wherein the magnetic field sensor further comprises;
a second full bridge circuit disposed upon the substrate and proximate to the ferromagnetic target object, comprising;
a fifth magnetoresistance element;
a sixth magnetoresistance element, the fifth and sixth magnetoresistance elements proximate to each other forming a third proximate pair;
a seventh magnetoresistance element;
an eighth magnetoresistance element, the seventh and eighth magnetoresistance elements proximate to each other forming a fourth proximate pair;
a second noninverting output node joining a selected two of the fifth, sixth, seventh, and eighth magnetoresistance elements; and
a second inverting output node joining a different selected two of the fifth, sixth, seventh, and eighth magnetoresistance elements, wherein a second differential signal is generated between the second noninverting node and the second inverting node, wherein the magnetic field sensor further comprises;
a first combining circuit disposed upon the substrate and configured to combine the first differential signal and the second differential signal to generate a feature signal having a largest value when a ferromagnetic target object feature is centered with the first and second full bridge circuits; and
a second combining circuit disposed upon the substrate and configured to combine the first differential signal and the second differential signal to generate an edge signal having a largest value when the first full bridge circuit is on one side of an edge of a ferromagnetic target object feature and the second full bridge circuit is on the other side of the same edge.
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Abstract
A magnetic field sensor operates as a motion detector for sensing a movement of a ferromagnetic target object having features. The magnetic field sensor has a plurality of magnetoresistance elements to generate, in a first channel, a feature signal indicative of a proximity of a feature of a ferromagnetic target object and, in a second channel, an edge signal indicative of a proximity of an edge of a feature of a ferromagnetic target object.
353 Citations
25 Claims
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1. A magnetic field sensor for sensing a movement of a ferromagnetic target object having ferromagnetic target object features with a target feature width, comprising:
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a substrate; a first full bridge circuit disposed upon the substrate and proximate to the ferromagnetic target object, comprising; a first magnetoresistance element; a second magnetoresistance element, the first and second magnetoresistance elements proximate to each other forming a first proximate pair; a third magnetoresistance; a fourth magnetoresistance element, the third and fourth magnetoresistance elements proximate to each other forming a second proximate pair; a first noninverting output node joining a selected two of the first, second, third and fourth magnetoresistance elements; a first inverting output node joining a different selected two of the first, second, third and fourth magnetoresistance elements, wherein a first differential signal is generated between the first noninverting node and the first inverting node, wherein the magnetic field sensor further comprises; a second full bridge circuit disposed upon the substrate and proximate to the ferromagnetic target object, comprising; a fifth magnetoresistance element; a sixth magnetoresistance element, the fifth and sixth magnetoresistance elements proximate to each other forming a third proximate pair; a seventh magnetoresistance element; an eighth magnetoresistance element, the seventh and eighth magnetoresistance elements proximate to each other forming a fourth proximate pair; a second noninverting output node joining a selected two of the fifth, sixth, seventh, and eighth magnetoresistance elements; and a second inverting output node joining a different selected two of the fifth, sixth, seventh, and eighth magnetoresistance elements, wherein a second differential signal is generated between the second noninverting node and the second inverting node, wherein the magnetic field sensor further comprises; a first combining circuit disposed upon the substrate and configured to combine the first differential signal and the second differential signal to generate a feature signal having a largest value when a ferromagnetic target object feature is centered with the first and second full bridge circuits; and a second combining circuit disposed upon the substrate and configured to combine the first differential signal and the second differential signal to generate an edge signal having a largest value when the first full bridge circuit is on one side of an edge of a ferromagnetic target object feature and the second full bridge circuit is on the other side of the same edge. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A magnetic field sensor for sensing a movement of a ferromagnetic target object having ferromagnetic target object features with a target feature width, comprising:
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a substrate; a first full bridge circuit disposed upon the substrate and proximate to the ferromagnetic target object, comprising; a first magnetoresistance element; a second magnetoresistance element, the first and second magnetoresistance elements proximate to each other forming a first proximate pair; a third magnetoresistance; a fourth magnetoresistance element, the third and fourth magnetoresistance elements proximate to each other forming a second proximate pair; a first noninverting output node joining a selected two of the first, second, third and fourth magnetoresistance elements; a first inverting output node joining a different selected two of the first, second, third and fourth magnetoresistance elements, wherein a first differential signal is generated between the first noninverting node and the first inverting node, wherein the magnetic field sensor further comprises; a second full bridge circuit disposed upon the substrate and proximate to the ferromagnetic target object, comprising; a fifth magnetoresistance element; a sixth magnetoresistance element, the fifth and sixth magnetoresistance elements proximate to each other forming a third proximate pair; a seventh magnetoresistance element; an eighth magnetoresistance element, the seventh and eighth magnetoresistance elements proximate to each other forming a fourth proximate pair; a second noninverting output node joining a selected two of the fifth, sixth, seventh, and eighth magnetoresistance elements; and a second inverting output node joining a different selected two of the fifth, sixth, seventh, and eighth magnetoresistance elements, wherein a second differential signal is generated between the second noninverting node and the second inverting node, wherein the magnetic field sensor further comprises; a first combining circuit disposed upon the substrate and configured to combine the first differential signal and the second differential signal to generate a feature signal having a largest value when a ferromagnetic target object feature is centered with the first and second full bridge circuits; and a second combining circuit disposed upon the substrate and configured to combine the first differential signal and the second differential signal to generate an edge signal having a largest value when the first full bridge circuit is on one side of an edge of a ferromagnetic target object feature and the second full bridge circuit is on the other side of the same edge, wherein the second proximate pair is disposed between the first and third proximate pairs, and wherein the third proximate pair is disposed between the second and fourth proximate pairs, wherein a spacing between the first and third proximate pairs is selected to be between about one half and about two times the target feature width, and a spacing between the second and fourth proximate pairs is selected to be between about one half and about two times the target feature width, the magnetic field sensor further comprising; an electronic circuit disposed upon the substrate, coupled to receive the feature signal and the edge signal, wherein the electronic circuit is operable to compare the edge signal with one or more threshold values to generate a first two-state signal and operable to compare the feature signal with another one or more threshold values to generate a second two-state signal, wherein an output signal generated by the magnetic field sensor comprises a signal encoding that identifies an alignment of state transitions of a selected one of the first or the second two-state signal. - View Dependent Claims (24, 25)
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Specification