Magnetic field sensor with magnetoresistance elements and conductive-trace magnetic source
First Claim
1. A magnetic field sensor comprising:
- a substrate;
a first magnetoresistive element supported by the substrate;
a second magnetoresistive element supported by the substrate and coupled in series with the first magnetoresistive element to form a voltage node between the first and second magnetoresistive elements and at which an output voltage is provided that changes in response to an external magnetic field; and
a magnetic source producing a local magnetic field having a strength sufficient to bias the first magnetoresistive element to a resistive value that is substantially resistant to changing in response to the external magnetic field;
wherein the magnetic source comprises a conductive trace supported by the substrate and configured to carry a current to provide the local magnetic field.
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Abstract
In an embodiment, a magnetic field sensor comprises a substrate and a first magnetoresistive element supported by the substrate. The magnetic field sensor also includes a second magnetoresistive element supported by the substrate and coupled in series with the first magnetoresistive element to form a voltage node between the first and second magnetoresistive elements, and at which an output voltage is provided that changes in response to an external magnetic field. The magnetic field sensor also includes a magnetic source that produces a local magnetic field having a strength sufficient to bias the first magnetoresistive element to a resistive value that is substantially resistant to changing in response to the external magnetic field. In embodiments, additional magnetoresistive elements are included to form an H-bridge circuit.
79 Citations
18 Claims
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1. A magnetic field sensor comprising:
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a substrate; a first magnetoresistive element supported by the substrate; a second magnetoresistive element supported by the substrate and coupled in series with the first magnetoresistive element to form a voltage node between the first and second magnetoresistive elements and at which an output voltage is provided that changes in response to an external magnetic field; and a magnetic source producing a local magnetic field having a strength sufficient to bias the first magnetoresistive element to a resistive value that is substantially resistant to changing in response to the external magnetic field; wherein the magnetic source comprises a conductive trace supported by the substrate and configured to carry a current to provide the local magnetic field. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A magnetic field sensor comprising:
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a substrate; first magnetoresistive element supported by the substrate; a second magnetoresistive element supported by the substrate and coupled in series with the first magnetoresistive element to form a first voltage node between the first and second magnetoresistive elements at which an output voltage is provided that changes in response to an external magnetic field; and a third magnetoresistive element supported by the substrate; a fourth magnetoresistive element supported by the substrate and coupled in series with the third magnetoresistive element to form a second voltage node between the third and fourth magnetoresistive elements and at which an output voltage is provided that changes in response to the external magnetic field; a first magnetic source positioned adjacent to the first magnetoresistive element and producing a first local magnetic field having a strength sufficient to bias the first magnetoresistive element to a resistive value that is substantially resistant to changing in response to the external magnetic field; and a second magnetic source positioned adjacent to the third magnetoresistive element and producing a second local magnetic field having strength sufficient to bias the third magnetoresistive element to a resistive value that is substantially resistant to changing in response to the external magnetic field; wherein the first and second magnetoresistive elements have a temperature coefficient that is substantially the same and the third and fourth magnetoresistive elements have a temperature coefficient that is substantially the same, so that the magnetic field sensor produces an output between the first and second voltage nodes that is substantially invariant in response to changes of temperature; wherein the first and second magnetic sources comprise conductive traces supported by the substrate and configured to carry current to provide the respective first and second local magnetic fields.
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Specification