Method and apparatus for magnetic sensor producing a changing magnetic field
First Claim
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1. A magnetic field sensor comprising:
- a semiconductor substrate;
a coil, supported by the semiconductor substrate, having a first terminal winding and a second opposite terminal winding, the coil configured to provide a changing magnetic field having a magnetic field vector with a direction parallel to a surface of the semiconductor substrate on which the coil is supported in response to a changing current in the coil; and
a plurality of magnetic field sensing elements arranged in a bridge configuration and supported by the substrate to detect a target by detecting variations in the changing magnetic field caused by the target;
wherein the target is physically separate from the semiconductor substrate; and
wherein a first pair of magnetic field sensing elements of the bridge configuration is positioned on the semiconductor substrate adjacent to the first terminal winding of the coil and a second pair of magnetic field sensing elements of the bridge configuration is positioned on the semiconductor substrate adjacent to the second terminal winding of the coil to increase a sensitivity of the magnetic field sensor to a target located in line with the magnetic field vector.
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Abstract
Methods and apparatus for detecting a magnetic field include a semiconductor substrate, a coil configured to provide a changing magnetic field in response to a changing current in the coil; and a magnetic field sensing element supported by the substrate. The coil receives the changing current and, in response, generates a changing magnetic field. The magnetic field sensing element detects the presence of a magnetic target by detecting changes to the magnetic field caused by the target and comparing them to an expected value.
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Citations
20 Claims
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1. A magnetic field sensor comprising:
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a semiconductor substrate; a coil, supported by the semiconductor substrate, having a first terminal winding and a second opposite terminal winding, the coil configured to provide a changing magnetic field having a magnetic field vector with a direction parallel to a surface of the semiconductor substrate on which the coil is supported in response to a changing current in the coil; and a plurality of magnetic field sensing elements arranged in a bridge configuration and supported by the substrate to detect a target by detecting variations in the changing magnetic field caused by the target; wherein the target is physically separate from the semiconductor substrate; and wherein a first pair of magnetic field sensing elements of the bridge configuration is positioned on the semiconductor substrate adjacent to the first terminal winding of the coil and a second pair of magnetic field sensing elements of the bridge configuration is positioned on the semiconductor substrate adjacent to the second terminal winding of the coil to increase a sensitivity of the magnetic field sensor to a target located in line with the magnetic field vector. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of detecting a magnetic field by a magnetic field sensor comprising:
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providing a magnetic field sensor having a semiconductor substrate; driving a changing current through a coil so that the coil generates a changing magnetic field having magnetic field vector with a direction parallel to a surface of the semiconductor substrate on which the coil is supported, the coil having a first terminal winding and a second, opposite terminal winding; and detecting, with a plurality of magnetic field sensing elements supported by the substrate, a target by detecting variations in the changing magnetic field caused by the target; wherein the target is physically separate from the semiconductor substrate; and wherein the plurality of magnetic field sensing elements are positioned in a bridge configuration, a first pair of magnetic field sensing elements of the bridge configuration is positioned adjacent to the first terminal winding of the coil and a second pair of magnetic field sensing elements of the bridge is positioned at adjacent to the second terminal winding of the coil to increase a sensitivity of the magnetic field sensor to a target located in line with the magnetic field vector. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A magnetic field sensor comprising:
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a semiconductor substrate; a coil configured to provide a changing magnetic field having a magnetic field vector with a direction parallel to a surface of the semiconductor substrate on which the coil is supported in response to a changing current in the coil, the coil having a first terminal winding and a second, opposite terminal winding; and a magnetoresistive transducer comprising a plurality of giant magnetoresistive (GMR) elements in a bridge configuration supported by the substrate to detect a target by detecting variations in the changing magnetic field caused by the target; wherein a first pair of GMR elements of the bridge configuration is positioned adjacent to the first terminal winding of the coil and a second pair of GMR elements of the bridge configuration is positioned adjacent to the second terminal winding of the coil to increase a sensitivity of the magnetic field sensor to a target located in line with the magnetic field vector; wherein the target is physically separate from the semiconductor substrate.
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20. A method of detecting a magnetic field comprising:
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providing a magnetic field sensor having a semiconductor substrate; driving a changing current through a coil so that the coil generates a changing magnetic field having a magnetic field vector with a direction parallel to a surface of the semiconductor substrate on which the coil is supported; detecting, with a magnetic field sensing element comprising a plurality of giant magnetoresistive (GMR) elements forming a bridge configuration supported by the substrate, a target by sensing variations in the changing magnetic field caused by the target; and positioning a first pair of GMR elements of the bridge adjacent to a first terminal winding of the coil and positioning a second pair of GMR elements of the bridge adjacent to a second, opposing terminal winding of the coil to increase a sensitivity of the magnetic field sensor to a target located in line with the magnetic field vector; wherein the target is physically separate from the semiconductor substrate.
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Specification