The Detect And Research Of Non-ideal Factors In Capacitive Micro Accelerometer

Microaccelerometer have penetrated into our daily lives, its applications can be found from aerospace, automotive, industrial equipment, cell phones and game consoles. Due to the small size, low cost and good linearity, comb-type microaccelerometer become the representative of the new sensor. With the development of MEMS technology, the performance of microaccelerometer is improved, but there are still many shortcomings. In order to meet the requirements of aerospace and other high-end areas, measurement accuracy and stability of MEMS sensors should be continuous improvement. Therefore the improvement of the performances, such as resolution, bias, drift and sensitivity, has always been the focus of the microaccelerometer research.In an ideal condition microaccelerometer can be seen as a differential capacitance and the difference between the capacitance is linearly related to the input acceleration. However, the influence of structural, manufacture and package will result in some non-ideal factors in microaccelerometer, such as the initial mismatch of the effective capacitance, parasitic capacitance, contact resistance and capacitor leakage, non-ideal factors will produce a impact on the system noise and zero offset. Therefore, it’s very necessary to research on these non-ideal factors. The main research contents are:1. The detection principle of comb microaccelerometer is analyzed and a high-performance open-loop capacitive sensing circuit is designed. It provide a circuit foundation for research the influence of these non-ideal factors.2. The causes of these non-ideal factors and their impact on the system are analyzed. It provides a theoretical basis for the research.3. Different detection methods are designed and achieve an accurate detection of these non-ideal factors, it provide a data base for accurate quantify the impact of non-ideal factors.4. A precise electric model of the microaccelerometer is built. According to the actual model parameters the influence of non-ideal factors to the system noise and zero offset are calculated, and the noise and zero offset are tested too. In this paper also puts forward the corresponding optimization goals and optimization method.