谐振式MEMS磁传感器数字锁相放大器设计

Design of digital lock-in amplifier for resonant MEMS magnetic sensor

介绍了一种用于谐振式微机电系统(MEMS)磁传感器输出信号检测的数字锁相放大器。通过分析MEMS磁传感器的工作原理和输出信号特征,并根据相干解调原理,设计了数字锁相放大器,其中包括信号通道、参考通道和数字式相干解调器的设计。在数字式相干解调器的设计中,通过正交解调法来消除相位差对磁传感器灵敏度的影响,利用带通采样和降采样来降低硬件要求。将数字锁相放大器应用于磁传感器,顺利实现了对磁传感器输出信号的解调。测试结果具有良好线性度,其非线性度为0. 46%。

A digital lock-in amplifier for detecting the output signal of the resonant micro-electro-mechanical system( MEMS) magnetic sensor is introduced. According to working principle of magnetic sensor and the characteristics of magnetic sensor output signal,and combined with the principle of coherent demodulation,a digital lock-in amplifier including signal channel,reference channel and digital coherent demodulator is designed.In the design of digital coherent demodulator,the influence of phase difference on the magnetic sensor sensitivity is eliminated by the quadrature demodulation,the requirement of hardware is reduced by using band-pass sampling and down sampling. Applying the digital lock-in amplifier to the magnetic sensor,the demodulation of the magnetic sensor output signal is successfully realized. Test results indicate that the system has a good linearity and the nonlinearity is 0. 46 %.