Research On Interface ASIC For High-performance Triple-axis Silicon Gyroscopes With Digital Outputs

Silicon gyroscope,as a core device,has been widely used in aerosp ace and tactical weapon systems.Foreign silicon gyroscopes and corresponding interface circuits have always been implemented by chip integration thus realizing small size,low power consumption,low costs and mass applications.In recent years,our country has made a breakthrough in research of interface circuits for single-axis silicon gyroscopes and has developed corresponding integrated interface circuit chips.In practical applications,vast majority of triple-axis gyroscopes is required.Consequently,integration of interface circuits for triple-axis silicon gyroscopes has important research significance.There are significant differences between triple-axis and single-axis integration of silicon gyroscopes.Many circuit modules in the triple-axis interface ASICs can be shared by means of direct sharing or time-multiplexing which therefore improves the implemented integration.However,the sharing of signal paths induces a new noise issue.The connection of triple-axis sensing elements and interface ASIC causes the problem of different input lead lengths and corresponding parasitic capacitance.According to the operating principles of silicon gyroscopes,this paper proposes the overall architectural design of triple-axis interface ASIC integration through circuit resource reintegration to realize device sharing.Besides,it focuses on the problems of noise suppression and adaptive compensation in triple-axis interface ASICs and completes the development of corresponding interface ASIC.Firstly,noise theory of interface circuit is studied.The switching and multiplexing of signal paths in triple-axis silicon gyroscope interface circuit induce additional noises.One part of these noises are amplitude noises injected by multi-channel charge detection and sampling-and-holding.The else is phase noises resulting from resonance frequency jitter induced by inherent frequency differences of triple-axis sense elements in common drive loop,which further influences demodulation precision of angular velocity.Noise regularities and optimization methods of triple-axis silicon interface circuit can be achieved from respective theoretical models of amplitude and phase noises.Validity of noise models are verified by experiments for conducting low-noise interface circuit design and noise optimization of interface circuit.Next,adaptive compensation method of interface circuit is studied according to influences of different input parasitic capacitance.Dynamic characteristics including sensitivities of triple-axis gyroscopes are changed by long-lead connection between triple-axis sense elements and interface ASIC.System coefficient variances are effectively cancelled by adaptive compensation method in closed-loop feedback based on linear extensive state observation.Influences on output angular velocity of input parasitic capacitance variance are evidently suppressed.Consistency of triple-axis sensitivities are improved.Based on above research,standard 0.35?m BCD integrated circuit process parameters and design rules are employed for overall forward design of interface ASIC with digital outputs for high-performance triple-axis silicon gyroscopes.Main circuit modules include multiplexed auto-gain-control drive loop and precise angular velocity resolving sense loop realized by analog front-stage charge detection and multi-channel incremental analog-to-digital conversion for noise optimization and adaptive compensation.Besides,pre-and post-simulations,layout design and tape-out have been carried out.The overall system is tested with gyroscope sense elements.Experimental results show triple-axis bias stability of 1.18°/h,1.19°/h and1.21°/h.Respective nonlinearities are 0.013%,0.015%,0.015%.The validity of chip design is verified by experimental results.Comprehensive performances achieve application requirements for high-performance triple-axis silicon gyroscopes.The research results of this paper have reference values for development of multi-axis integrated inertial measurement devices.