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Methods and apparatus for magnetic sensor having integrated coil

  • US 9,817,078 B2
  • Filed: 05/10/2012
  • Issued: 11/14/2017
  • Est. Priority Date: 05/10/2012
  • Status: Active Grant
First Claim
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1. A magnetic field sensor, comprising:

  • a die;

    a coil proximate the die to generate a magnetic field;

    a Hall element magnetic field sensing element on said die to detect changes in the magnetic field generated by the coil as a result of movement of a ferromagnetic target external to the magnetic field sensor;

    a constant current source coupled to the coil such that alignment changes of the magnetic field generated by the coil with respect to the magnetic sensing element caused by movement of the target are detected by the magnetic field sensing element,wherein the movement of the ferromagnetic target to a first position causes a vector of the magnetic field generated by the coil to align substantially perpendicularly to the magnetic field sensing element which increases the magnetic field observed by the magnetic field sensing element, and further movement of the ferromagnetic target to a second position changes the magnetic field observed by the magnetic field sensing element; and

    a GMR magnetic sensing element positioned in relation to the coil, wherein the Hall element magnetic sensing element is configured for a first airgap distance, and the GMR magnetic sensing element is configured for a second airgap distance, which is greater than the first airgap distance.

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