Research Of Zero Bias And Temperature Characteristics For High Precision Capacitive Mems Accelerometer

Micro-electro-mechanical system is an industry technology of combining both microelectronics and mechanical engineering together. For its fast response, high sensitivity, high precision, miniaturization, wide applicability, and low power consumption, it has been widely concerned both at home and abroad.Zero bias, which is an important indicator in evaluating the dynamic performance of micro-accelerometer, can be affected by the structure of capacitive micro-machined accelerometer and its capacitance detecting circuit. Meanwhile, temperature is the most important environmental factor affecting the performance of micro-accelerometer. Reducing the temperature drift is beneficial to improving the measuring accuracy and the bias stability, which can expand the application range of the micro-accelerometer.Zero bias and zero offset of the capacitive accelerometer are the primary objects of study in this work. Zero bias decreases after static electricity compensation. The performance of the micro-accelerometer system is improved greatly. Meanwhile, a MEMS resistor based temperature compensation method is put forward and the temperature drift is improved remarkably.The major work and innovations of this thesis contains:(1)The main zero bias sources, such as the asymmetric measuring circuit, the method of demodulation, the initial capacitance sensor and so on, are studied based on capacitive micro-machined accelerometer.(2)A method to decrease the initial differential capacitor of the sensor by static electricity is puts forward. Test results show that, after static electricity compensation, the accelerometer’s zero bias stability decreases from0.2617mg to0.2333mg, zero offset decreases from0.4175mg/℃to0.3094mg/℃, zero bias repeatability decreases from2.7197mg to1.8727mg.(3)A temperature compensation method based on MEMS resistor is put forward. It doesn,t require additional compensation circuit and can reduce the area of the circuit. Test results show that, after temperature compensation, the accelerometer’s zero bias stability decreases from0.2333mg to0.1423mg, zero offset decreases from0.3094mg/℃to0.1202mg/℃.