Method for evaluating signals of magnetoresistive sensors with high band width
First Claim
1. A method for evaluating signals with elimination of an interference signal proportional to the zero offset on a magnetoresistive sensor element, in which the directions of magnetization are reversed in said magnetoresistive sensor element having a Barber pole structure by application of a magnetic pulse field with an alternating direction, and an output voltage of said sensor element is fed to a differential amplifier, wherein the polarity of an operating voltage of said sensor element is changed at the cycle of said magnetic pulse field;
- that said output voltage of said sensor element is amplified by said differential amplifier and fed back to a low-pass via a reversing switch controlled at the cycle of said magnetic pulse field, and from the output of said low-pass fed back inphase to the input of said differential amplifier via an amplifier and a second reversing switch controlled at the cycle of said magnetic pulse field; and
that the alternating component conditioned by the offset component of said output signal of said sensor element is controlled to zero in this way on the output of said differential amplifier.
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Abstract
The invention relates to a method for evaluating signals while eliminating an interference signal on magnetoresistive sensor elements which is preferably proportional to the zero offset. The sensor elements can form a sensor element array such as a sensor bridge. According to the invention, the direction of magnetization of the sensor elements is modulated or shifted by applying a magnetic pulse field of a modulated or variable direction, and the output signals of the sensor elements or of the sensor element array are fed to a differential amplifier. Due to the modulation or shift of the operating voltage of the sensor bridge, the modulation or shift resulting at the same time as the magnetization of the sensor elements, a signal often arises which includes a direct component that is proportional to the magnetic field to be measured, and has an alternating component that is proportional to the offset voltage of the sensor element array. The latter is minimized by a feedback or is adjusted to zero. The bandwidth, with which the direct voltage that is proportional to the magnetic field to be measured can follow changes of the input signal, is greater in magnitude than the magnetization frequency of the sensor elements.
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Citations
12 Claims
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1. A method for evaluating signals with elimination of an interference signal proportional to the zero offset on a magnetoresistive sensor element, in which the directions of magnetization are reversed in said magnetoresistive sensor element having a Barber pole structure by application of a magnetic pulse field with an alternating direction, and an output voltage of said sensor element is fed to a differential amplifier, wherein the polarity of an operating voltage of said sensor element is changed at the cycle of said magnetic pulse field;
- that said output voltage of said sensor element is amplified by said differential amplifier and fed back to a low-pass via a reversing switch controlled at the cycle of said magnetic pulse field, and from the output of said low-pass fed back inphase to the input of said differential amplifier via an amplifier and a second reversing switch controlled at the cycle of said magnetic pulse field; and
that the alternating component conditioned by the offset component of said output signal of said sensor element is controlled to zero in this way on the output of said differential amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
- that said output voltage of said sensor element is amplified by said differential amplifier and fed back to a low-pass via a reversing switch controlled at the cycle of said magnetic pulse field, and from the output of said low-pass fed back inphase to the input of said differential amplifier via an amplifier and a second reversing switch controlled at the cycle of said magnetic pulse field; and
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