基于正交锁定差分放大器的巨磁阻抗(GMI)磁传感器

Giant magnetoimpedance( GMI) magnetic sensor based on orthogonal lock-in differential amplifier

基于非晶丝的巨磁阻抗(GMI)效应,利用CoFeBSi非晶丝作为敏感材料,采用正交锁定放大电路和仪用放大器作为信号调理电路,设计了一种差分式高灵敏度GMI磁传感器。介绍了巨磁阻抗效应的基本概念和双非晶丝差分结构的磁敏探头,分析了基于正交锁定差分放大技术的信号调理电路的工作原理,并结合非晶丝两端输出信号的幅度和相位特性,提出了正交锁定放大器输出包络的近似计算方法。实验结果表明:在-2.0 Oe^+2.0 Oe的量程内,该GMI磁传感器灵敏度可达748mV/Oe,线性误差为0.98%FS,且噪声平均功率谱密度约为0.8nT/Hz1/2。

On the basis of the giant magnetoimpedance（ GMI） effect found in the amorphous wire,and with the utilization of the CoFeBSi amorphous wire as the sensing material,a novel differential-type high sensitively sensor adopting the technology of orthogonal lock-in amplifier was designed. Firstly,the concept of the GMI effect and the magnetic sensing head based on the double-sensing-elements and differential-type structure,were briefly instructed. Secondly,the principle of the conditioning circuit of the sensor based on orthogonal lock-in amplifier was analyzed in detail. Thirdly,based on the impedance magnitude and phase characteristics of the amorphous wire,an approximate algorithm was put forward to calculate the envelope of the output of the orthogonal lock-in amplifier for simplifying the arithmetic circuit. Experiment results show that the sensitivity of the sensor can achieve about 748mV / Oe with the full measurement range of- 2. 0Oe ～ ＋ 2. 0Oe,and the linearity error is about 0. 98% FS,while the average noise power spectral density is about 0. 8nT / Hz1 /2.