Hysteresis Suppressing of Modulated Magnetoresistive Sensors Using Bidirection Pulse Magnetization

1/f noise as well as nonlinear and hysteresis are the dominant restrictions of magnetoresistive (MR) sensors in detection ability. Modulation of the stimulating magnetic field of the MR sensors with microelectromechanical systems (MEMS) can reduce the 1/f noise by hundreds of times at low frequency, which gives a highlight for high-sensitive magnetic sensors. However, nonlinear response primarily caused by magnetic hysteresis is still a practical problem in modulated MR sensors, as well as unipolar response. In this paper, we propose a bidirection pulse magnetization method to reduce magnetic hysteresis, and in order to separate MR sensors from temperature influence, an integrated MEMS structure with low dissipation is developed to achieve pulse magnetization. Furthermore, this method is also used to achieve the bipolar magnetic field detection by distinguishing the response disparity under bidirection magnetization. The experimental results show that the modulated MR sensors can realize 90% reduction of hysteresis and 12.9% improvement of sensitivity with this method.