A Dual Quantization Electromechanical Sigma-delta Modulator MEMS Angular Vibratory Gyroscope

With the advantages of low cost,small size,high reliability and low power consumption,MEMS gyroscope has been widely used in automotive,electronics,aerospace and other fields compared to traditional gyroscope.Many countries have taken it as one of the priority technologies must be focused.High quality factor gyroscope sensing elements combined with low noise pick-off circuit technology and mode-matching technology greatly improved the performance while must works in closed-loop due to the sensitivity-bandwidth tradeoff.Electromechanical sigma-delta modulation technology gives the solution with its low noise digitization and closed-loop operation which makes it an important technology of navigation grade inertial sensors.This paper presents a dual quantization electromechanical sigma-delta modulator MEMS angular vibratory gyroscope.Giving the system architecture,theoretical calculation,and model simulation and test results based on angular vibratory gyroscope and sigma-delta modulator.Firstly,an introduction of mechanical structure and angular rate detecting principles.Giving the application of sigma-delta modulation into the inertial sensors based on noise shaping,oversampling technologies.Secondly,a system architecture of the dual quantization electromechanical sigma-delta modulator MEMS angular vibratory gyroscope was presented.Based on the quasi linear model of the sense loop,the loop stability and noise shaping were analyzed.The characteristics analyzed in the quasi linear model was validated by real-time simulation in Simulink.Lastly,the hardware implantation and test results.Low-noise front-end ASIC translates capacitance changes to analog voltage signals.The mixed-signal system with ADCs and DACs connect the analog and digital system.The algorithms of drive loop and sense loop are implanted in the FPGA based digital signal processing system.The feedback pulse coupling due to the parasitic capacitances,feedback spectrum aliasing and filter delay were researched.Finally,the digitalized system achieved a scale factor of 1/ °/ s,with a linearity of 0.046% in the ±300°/ s dynamic range,noise of 3.1m°/ s/ (?),bandwidth of 100 Hz,and the bias instability of 1.3°/ h,which reaches the medium tactical grade.