Study On High-precision Quartz Vibrating Beam Accelerometer

The quartz vibration beam accelerometer(QVBA)is a resonant accelerometer based on the inverse piezoelectric effect of quartz and stress frequency effect of the resonance beam.Due to its detection mechanism and the excellent characteristics of the material,it is widely used for its high precision.To be specific,it has a quasi-digital output,which is convenient for transmission as well as processing.It also has advantages such as stable temperature characteristics,long-term reliability,low cost,and convenience for mass production.In order to apply the QVBA to the field of high precision,this paper proposed a high precision QVBA based on the monolithic quartz vibration beam accelerometer,designed by research group,by using the optimization of the structural design and the design of the full digital measurement and control system.On the basis of achieving high precision,the hinge rotation angle was introduced,and the influence of the pull-in phenomenon on the electrode plate spacing was analyzed in detail.In order to overcome the non-conductivity between the active part and the electrode plate,a batch of test pieces was designed to verify the feasibility of the process.Firstly,this paper introduced the working principle of the QVBA,and optimized the mechanical analysis of the active part by considering the hinge rotation angle for the first time.The influence of substrate thickness,mass size,and resonance beam size on the scale factor was refined through theoretical analysis and ANSYS simulation.From the simulation results,the sensitivity can reach 657.5Hz/g,and the range can reach ± 8g.Secondly,two models were established for electrode plate,and the relationship between the plate spacing,the pull-in voltage and the actual applied accelerometer was clarified.It was confirmed that105μm was adequate for spacing.Thirdly,the test chip was manufactured and the mask process and H20 E was verified to be feasible.Finally,a high-precision frequency measurement system was designed based on FPGA-TDC,and the feasibility of the design is verified by Modelsim.