Temperature Characteristics Of Silicon Micro-resonant Accelerometer

With high precision, wide dynamic range, small size and low power consumption, silicon resonant accelerometer (SRA) potentially earns a wide application spectrum in the military, civil fields. SRA has become a hot research topic for MEMS inertial sensors. We aim to further improve the performance of SRA. In this paper, the key objectives mainly from the research of nonlinear vibration and temperature characteristics of SRA are as follows:Firstly, the operating principles of SRA is studied. The mathematical model of the resonator is with one end fixed and the other end connected to a flexible structure. The vibration equation and mode parameters are deduced and the relationship between resonant frequency and axial force is built. The natural frequency is validated preliminarily through simulations and experiments. The mathematical models of micro-lever system and supporting system are built, the amplification factor and stiffness of which are theoretically analyzed and simulated by FEA. The main performances of SRA are illustrated.Secondly, for the nonlinear vibration of resonator, the relationship between vibration amplitude and resonant frequency is induced with the method of harmonic balancing. The 3rd order elastic coefficient is induced by theoretical analysis and simulation, and the nonlinear coefficient is derived. Then the nonlinear vibration characteristic of resonator is simulated by FEA. The relationship between vibration amplitude and driving voltage is derived and validated by the nonlinear experiments.Thirdly, the temperature characteristic of SRA is researched. The temperature influence mechanism of SRA is studied. Focusing on bias and scale factor (SF), it is analyzed separately the influence of Young modulus and residual stress on the performance parameters. The simulations and experiments are carried out to validate the temperature sensitivity of bias and SF. The temperature influence is also considered under the processing error. The residual stress is proved the main factor which causes temperature shift, and the isolation beams to isolate the residual stress are designed. The main methods of temperature compensation at home and abroad are introduced. A temperature compensation measure based on electrostatic stiffness is proposed and the scheme is simulated by simulink.Finally, the performance of the whole optimized SRA is tested. The ways to improve the structure and the main parameters of SRA are analyzed. The stability and repeatability of bias value, the stability and repeatability of SF, and the temperature characters of SRA prototype are tested. The testing results indicate that the optimization of structure can reduce residual stress and the temperature sensitivity. The temperature sensitivity of bias and SF are reduced to 24% and 2% of the original value respectively.