MEMS陀螺仪ΣΔ闭环系统优化设计

Optimization Design of ΣΔ Closed-Loop System for MEMS Gyroscope

为解决传统ΣΔ闭环控制系统存在的量化增益不可控问题,设计了基于3-level量化技术的改进系统;针对此系统应用于微电子机械系统(MEMS)陀螺仪时引入的非线性反馈误差,提出了一种调整反馈脉冲宽度的矫正技术;并基于课题组研制的新型类蛛网环式谐振陀螺仪验证了改进系统的实用性。首先采用Simulink建立了四阶机电耦合ΣΔ系统等效模型,理论分析与仿真结果表明,3-level量化技术在降低量化噪声的同时解决了量化增益不可控问题,进而有效提高了陀螺仪量程和噪声水平性能。然后基于现场可编程逻辑门阵列(FPGA)设计制作了相应的数字测控电路,实验结果显示,陀螺仪的角度随机游走由0.094°/√h降低为0.062°/√h,量程由100°/s提高到130°/s,系统性能得到了有效提升。

In order to solve the problem of uncontrollable quantization gain in the traditionalΣΔclosed-loop control system,an improved system based on 3-level quantization technology was designed.However,nonlinear feedback errors were introduced when the system was applied to micro-electromechanical system(MEMS)gyroscopes,for which a correction technique for adjusting the feedback pulse width was proposed.The practicability of the improved system was verified in the new cobweb-like ring resonator gyroscope developed by the research group.Firstly,the equivalent model of the fourth-order electro-mechanical couplingΣΔsystem was established in Simulink.Theoretical analysis and simulation results show that 3-level quantization technology solves the problem of uncontrollable quantization gain,and meanwhile the quantization noise is reduced,thereby significantly improving the gyroscope range and noise level performance.Then,the corresponding digital measurement and control circuit was designed and fabricated based on the field programmable gate array(FPGA).The test results show that the angle random walk of the gyroscope is reduced from0.094°/√h to 0.062°/√h,the range is increased from100°/s to130°/s,and the system performance is improved effectively.