So exploration and research on high performance micro accelerometers is still a hot research topic. For high performance, two aspects are focused on. One is the exploration of new principles and novel structures, and the other is the design of an appropriate signal detecting circuit, which will directly influence the characteristics of the accelerometer system.Since the vacuum microelectronic technology was proposed in 1988, the possibility of producing a high precision, good performance vacuum microelectronic sensor has been actively explored. The study of vacuum microelectronic sensors started in 1991, and since then many new types of sensors have appeared , such as pressure sensors, accelerometers, magnetism sensors and image sensors.
Vacuum microelectronic devices are designed based on field emission theory, and the sensing part works under vacuum conditions. It utilizes the cold cathode to emit electrons, the emission current density is mainly determined by the electric field density near the tip array, which is exponential to the distance between the anode and the cathode tip array. Compared to other common well-developed accelerometers, vacuum microelectronic accelerometer has unique advantages of anti-radiation, small size, high sensitivity and the compatibility for fabrication process with integrated circuits (IC). It is widely required in applications such as small satellites, navigation, dexterous projectiles, tactical missiles and industrial automatic control .The signal detecting circuit is another essential part for high precision micro accelerometers, and considerable research work has been done in this area too.
Analog Devices Company has designed a modulation and demodulation circuit for capacitive accelerometers since the 1990s . Now it is integrated with an accelerometer on a chip, and the accelerometer has good performance. Stanford Integrated Circuit Laboratory developed a high precision tunneling accelerometer and the corresponding closed-loop control circuit in 1998. This accelerometer can attain micro-g resolution . Nowadays, several groups have begun to study the influence of signal detecting circuits on the characteristics of accelerometer systems. Based on the system modeling, they do analysis of the system using Matlab software, and then attain appropriate circuit parameters to instruct the design of signal detecting circuits [8-9].
The objectives of the present research are to design a signal detecting circuit for a high precision vacuum microelectronic accelerometer, which will ensure good linearity, high sensitivity and fast response of Entinostat the accelerometer system. In this paper, first the structure and working principles of a vacuum microelectronic accelerometer are introduced, and then the mathematical model is established.