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Method of auto calibrating a magnetic field sensor for drift and structure therefor

  • US 8,134,358 B2
  • Filed: 10/16/2007
  • Issued: 03/13/2012
  • Est. Priority Date: 10/16/2006
  • Status: Active Grant
First Claim
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1. A method to compensate a sensitivity drift of a magnetic field sensor for sensing a magnetic field BExt, the sensor comprising at least four electrodes, the method comprising:

  • a first step where a first set of two electrodes of the at least our electrodes is used to bias the sensor and a second set of two electrodes of the at least four electrodes is used to sense an output signal of the magnetic field sensor; and

    a second step where the second set of two electrodes is used to bias the sensor and the first set of two electrodes is used to sense another output signal of the magnetic field sensor;

    the method being characterized in that;

    the second step is subdivided in at least a first sub-step and a second sub-step, a reference magnetic field having first magnetic field parameters in the first sub-step and second magnetic field parameters in the second sub-step wherein during both the first step and one of the first and second sub-steps of the second step the reference magnetic field has a first amplitude and a first phase for both the first step and the one of the first and second sub-steps and during only one of the first or second sub-steps the reference magnetic field has one of a) a greater amplitude than the first amplitude and has the first phase, or b) a zero amplitude;

    the output signal is sensed in the first step and the another output signal is sensed in the second step; and

    the another output signal is sensed within the first and second sub-step.

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