FIR数字滤波在MEMS加速度计中的应用

Application of FIR Digital Filters in MEMS Accelerometers

简要分析了MEMS加速度计应用模型中的噪声来源,介绍了FIR数字低通滤波器的设计方法,并用FPGA实现的FIR滤波器对MEMS加速度计的输出信号进行了实时滤波处理。通过对滤波前后时、频域信号的比较,可以看出采用FIR数字低通滤波器能有效抑制加速度计输出信号中的高频噪声、提高加速度计的测量精度。实验结果表明,滤波前噪声信号标准偏差为1.53×10-5V,经FIR数字低通滤波后的噪声信号标准偏差降低为5.4×10-6V,加速度计的分辨率由126μg提高到42μg。

The noises of the MEMS accelerometers model were briefly analyzed. Design method of the FIR lowpass filter was introduced. And the output signal of MEMS accelerometers was filtered continuously by the FIR filter which was implemented by FPGA. Comparing the output spectra of the accelerometer before and after filter, the result shows that the FIR digital lowpass filter can effectively restraine the high frequency noises of the MEMS accelerometer and improve the measure precision of the MEMS accelerometer. The experiment result shows that the signal standard deviation of the accelerometer is reduced from 1.53 × 10^-5 V to 5.4 × 10^-6 V, and the resolution of the accelerometer is improved from 126 μg to 42 μg.