High-resolution MOEMS Accelerometer Signal Processing System Design

A set of signal processing system for the high-resolution of the MOEMS accelerometer is designed in this paper. MOEMS accelerometer combines optics technology and micro-machining technology, which not only has the advantages of small size, fast response, can work in harsh environment etc., but also has the very high measuring accuracy and sensitivity. MOEMS accelerometer is the most promising acceleration sensor in inertial navigation and guidance systems in national defense and military fields. MOEMS accelerometer with high-resolution needs low noise signal processing system. In order to realize the high acceleration measurement precision, the completion of the development of signal processing system with low noise, high precision is an important part. And for the integration and miniaturization realization of MOEMS accelerometer, the selection of appropriate system light source and design associated driver circuit are very necessary. Therefore, VCSEL integrated together with the signal adjusting circuit is chosen to be the light source. By this way, the integration of MOEMS accelerometer system can be greatly enhanced.The main research contents of this thesis is as follows:Firstly, we make a brief instruction to the measurement principle, application, research status and development tendency of the micro-accelerometer, and then make an analysis and comparison of the advantages and disadvantages of various micro-accelerometers. The research contents and object are also proposed.We introduce the displacement sensing mechanism and acceleration sensing mechanism of the MOEMS accelerometer based on the micro-structure grating briefly. Working principle of the accelerometer system is also explained.We make a summarization about several common signal processing schemes and introduce the realization process of the phase modulation-demodulation technique in this paper.The signal processing system of the MOEMS accelerometer is set up, including power supply design, selection of detector, follower and differential amplifier circuit design and the band-pass filter design. The system selects VCSEL as the light source. We design the constant current power and constant temperature control circuit corresponding.In order to verify the performance of the signal processing system, a single light path displacement measurement device is built. Through the experimental data, we obtain the dark noise of electrical circuit is 1.1 mv, and displacement measurement sensitivity is up to 40.21859V/μm. In order to make some compensation for the power fluctuation of He-Ne laser, which has an effect on the measurement accuracy in displacement device, we set up a dual light path displacement measuring device and design a double channel signal acquisition system corresponding.We apply this conditioning circuit and data capturing system designed by ourselves to the accelerometer, which has a plenty room to improve. Then we get the resolution of this accelerometer is 42.1μg, which means our prototype of accelerometer acquire the corresponding performance as the best accelerometers on sale.Finally, a summary of the research work is involved, and the future direction of the work is proposed.