反馈式巨磁阻抗弱磁传感器的设计与实现

Design and Realization of Feedback-type Giant Magneto-impedance Micro-magnetic Sensor

为提高基于巨磁阻抗(GMI)效应的弱磁传感器的性能,该文研究了Fe基非晶带在纵向激励下的GMI特性。建立和分析了传感器反馈模型,设计了反馈式GMI弱磁传感器。由CMOS集成反相器组成脉冲激励电路,由峰值检波电路、低通滤波电路、差分放大电路及电压跟随器组成信号调理电路,由仪用放大器、低通滤波电路、电阻和电感组成负反馈电路。利用亥姆霍兹线圈和标准恒流电源组成标定系统,对该传感器进行了加反馈和不加反馈两种情况下的对比测试。实验结果表明:在外加磁场强度为-2.5～2.5 Oe范围内,该反馈式GMI弱磁传感器较无反馈的GMI弱磁传感器的线性度指标提高了41%;传感器输出的漂移在不加反馈时为10～20 mV/h,加入负反馈后在无外加磁场时为2 mV/h,在外加磁场强度为2.5 Oe时为3 mV/h;传感器的截止频率在未加反馈时约为2 kHz,加入负反馈后提高到了4 kHz以上。

To improve the performance of a micro-magnetic sensor based on the giant magneto-impedance（GMI）effect,the GMI characteristic of Fe-based amorphous ribbon under longitudinal excitation is researched.A sensor feedback model is established and analyzed.A feedback-type GMI micro-magnetic sensor is designed.The excitation circuit is composed of complementary metal-oxide-semiconductor（CMOS）coupling reactor.The conditional circuit is composed of peak value detection circuit,low-pass filter circuit,difference amplifier and voltage follower.The feedback circuit is composed of instrumentation amplifier,low-pass filter circuit,resistor and inductor.Contrast tests are processed with or without feedback by a calibration system composed of Helmholtz coil and constant-current power.The results show that：with the external magnetic field strength of-2.5~2.5 Oe,the linearity index of the feedback-type GMI micro-magnetic sensor is improved by 41% compared with the GMI micro-magnetic sensor without feedback;the sensor drift is 10~20 mV/h without feedback and 2 mV/h with feedback without external magnetic field;when the external magnetic field strength is 2.5 Oe,the drift is 3 mV/h;the cutoff frequency of the sensor is 2 kHz without feedback and above 4 kHz with feedback.