PROJECT TITLE :

Hysteresis Compensation Based on Controlled Current Pulses for Magnetoresistive Sensors

ABSTRACT:

This paper presents a unique hysteresis compensation methodology for increasing the measurement accuracy of magnetoresistive (MR) sensors like anisotropic magnetoresistance (AMR), giant magnetoresistance (GMR), and tunnel magnetoresistance (TMR) sensors. A coil consisting of 1 winding is processed on top of the sensor element. This configuration allows short current pulses (positive and negative) to generate a defined magnet field, that should be much stronger than the sphere to be measured. In this case, the MR sensors can always be kept in the same magnetic loop (major loop) throughout the measurement cycle. By demodulating or averaging the output signal of the sensor, the influence of the sensors hysteresis will be largely reduced. A mixed signal circuit consisting of a field-programmable gate array, analog-to-digital converters and analog switches is employed to generate the pulses. AMR, GMR, and TMR current sensors are chosen as examples within the experiment. Current measurements with and without controlled magnetic field pulse are compared. A hysteresis reduction to just about 20% of the initial value, by using the novel hysteresis compensation technique, is reached.