高Q值超低功耗谐振式磁传感器的设计与实现

Design and fabrication of a resonant magnetic field sensor with high quality factor and low power consumption

针对现有谐振式磁传感器原理不能同时实现高品质因数(Q)和低功耗的缺点,利用双端固定石英音叉谐振器与铁镓磁致伸缩合金片复合,设计了一种隔离磁机阻尼的高Q值、数字频率输出的超低功耗谐振式磁传感器。利用音叉谐振器结构的解耦特性,设计应力耦合传递结构,隔离了磁致伸缩材料磁机阻尼,从而保证复合传感器Q值与音叉谐振器Q值相当。在磁场作用下,磁致伸缩力传递到音叉谐振器,由于音叉力敏感特性,实现磁-力-频率转换。制备了铁镓合金/石英音叉谐振器复合敏感结构,测试表明,在低气压封装条件下的品质因数约为16 764,门振荡电路功耗约为124.8μW,在线性区灵敏度为3.05 Hz/Oe,分辨率为6 mOe。

Aiming at the shortcomings of the existing resonant magnetic sensor principle that high quality(Q) factor and low power consumption cannot be achieved at the same time, a low-power resonant magnetic sensor with high Q-factor and digital frequency output is designed by combining the double-ended quartz crystal tuning fork(DETF) resonator with magnetostrictive FeGa plate. Using the decoupling characteristic of the structure of DETF resonator, the stress coupling structure is designed to isolate the magnetomechanical damping of the magnetostrictive material. Thus, the Q-factor of the composite sensor is almost equal to that of the DETF resonator. The magnetostrictive force occurring under magnetic field induces a longitudinal force in the DETF. The magnetic-force-frequency conversion is achieved due to the force sensitive characteristic of the DETF. A low pressure packaged sensors based on the composite structure of FeGa alloy and DETF resonator is fabricated. The test results show that the Q-factor and power consumption of the sensor are about 16 764 and 124.8 μW, respectively. In the linear region, the sensitivity and resolution are 3.05 Hz/Oe and 6 mOe, respectively.