基于∑-△M的五阶MFLR数字微加速度计闭环控制系统

为了进一步抑制加速度计信号带宽范围内的噪声,提出并设计了一种基于∑-△M的五阶多反馈谐振式（MFLR）微机械加速度计闭环控制系统,该系统通过增加额外的内部负反馈对量化噪声进行再一次整形.微机械加速度计结构为一种全差分式结构,在结构层厚度为60 μm、基底层厚度为400μm的SOI硅片上,经过光刻、溅射、深度反应离子刻蚀等工艺步骤加工而成.整个闭环控制系统的Matlab/Simulink模型首先被建立,然后采用“单位圆分析法”进行系统参数的设定,系统仿真显示：当输入幅值1gn、频率128Hz的加速度信号时,加速度计的噪声为-136.2 dB,与传统五阶MF结构的∑-△M闭环控制系统相比,在0 ～500 Hz信号带宽范围内的噪声降低了7.9dB.最后整个系统在四层PCB电路板上进行了功能性验证和测试.

Fifth-order MFLR digital closed-loop control system of MEMS accelerometer based on

In order to further depress noise in signal bandwidth, a fifth-order MEMS accelerometer closed-loop control system based on Sigma-Delta modulator （ E-AM ） with multi-feedback loops and resonators （ MFLR ） is proposed, this system through adding additional local feedback to shape the quantization noise structure of MEMS aecelerometer is fully differential structure which is manufactured on SOI wafer with structure layer thickness of 60 μm and substrate layer thickness of 400 μm, manufacturing procedure includes lithography, sputtering, deep reactive ion etching, etc. Matlab/Simulink model of overall closed-loop control system is firstly set up, then, system parameters are set by unit circle analysis method. System simulation show that power spectral density （PSD） simulation of the system is dSrived. The amplitude of input is 1 g, and frequency of signal is 128Hz, noise is --136.2 dB which is 7.9 dB lower than traditional 5 th-order closed-loop control system based on E-AM with MF topology, at range signal bandwidth of 0 -500 Hz. A four-layer printed circuit board（PCB） prototype of this system is built to validate functionality of the system and tested.