Hysteresis Compensation Method for Magnetoresistive Sensors Based on Single Polar Controlled Magnetic Field Pulses

Abstract

This paper presents an improved hysteresis compensation method based on magnetic field pulses. The magnetic field pulses are generated by current pulses applied to a one-winding coil structure on the top of the sensor element. This configuration allows the sensor electronic to drive a magnetoresistive (MR) sensor in its magnetic saturation. Anisotropic magnetoresistance, giant magnetoresistance, and tunnel magnetoresistance current sensors are chosen for conducting experiments. The magnetic field generated by current pulses and the magnetic field generated by the current to be measured always have to be in the same direction. As a result, the output characteristic of an MR current sensor can always be kept on the negative rising and the positive falling branch of the magnetic major loop during the measurement. Thus, a defined output of the MR current sensor independent from the magnetic history for all current values can be achieved. An electronic mixed signal circuit consisting of a field-programmable gate array, an optoisolator, analog switches, and attention display converters is used to generate the current pulses and to measure the output of the current sensor. Current measurements with and without controlled magnetic field (current) pulses are compared. A hysteresis reduction to nearly 20% of the original value, by using this hysteresis compensation method, was reached.