MEMS Gyroscope High Precision Analog/digit Conversion Technique Based On Sigma-delta Theory

Due to small volume, light weight, high reliability and easy integration, MEMS (micro-electromechanical Systems) gyroscopes have broad application prospect in the fields of automobile industry, aviation, aerospace and robotics. Extensive attention has been taken on MEMS gyroscope research and development from all over the world. The wide applications of MEMS gyroscope products have been realized in foreign countries. Meanwhile great progress on key techniques of MEMS gyroscope has been made in our nation in recent years. The room-temperature precision of MEMS gyroscope prototypes in our nations has approached the medium precision level of the corresponding foreign products, Due to poor temperature properties of the prototypes, there still exists a certain distance to satisfy the engineering application requirements. In order to improve the temperature performance of MEMS gyroscope prototypes, design improvement and process optimum have currently been adopted. In addition, to secure small volume, low power and low cost of MEMS gyroscopes, accurate measurement and compensation have been taken in the post processing of MEMS gyroscope testing system so as to improve comprehensive precision level in engineering environments, which is a very effective means to promote engineering applications.The high precision analog/digit conversion technique based on sigma-delta theory has been subjected. The principle and characteristics ofΣΔ-ADC have been researched. Mathematic model ofΣΔ-ADC has been applied. and over-sampling, noise modulation and numerical filter technology have been analyzed to improve the A/D converting precision. The advantages ofΣΔ-ADC in MEMS gyroscope signal measurement have been determined, and theΣΔ-ADC circuits have been designed. The high precision AD converting of MEMS gyroscope readout signal has been realized. Meanwhile, integration design of digital circuits has been fulfilled, where the FPGA chip imbedded with ARM processor and the flash memory chip have been adopted. The flash chip stores software codes and gyroscope measurement data. and the FPGA chip fulfill all other functions, so the ARM processor has the capability to process the gyroscope data and finish temperature compensation in cooperation with the time sequence controller. The test shows that the A/D converting precision and resolution have approached 18bit (superior to±1×10-5) and 20bit(superior to±1×10-6). respectively. The system guarantee the MEMS gyroscope's requirements of small size, low power, low cost, high precision and compensation ability, by using high precision analog/digit conversion and compact intellectual digital controller module. In addition, the system has a broad usability. The system has very good value to realize national MEMS gyroscope engineering application.