Design And Simulation Of Piezoresistive Accelerometer

MEMS accelerometer is one of the earliest development of MEMS sensors. It has been widely applied in automotive, military, medical, industrial control, Internet of Things, intelligent phone and other fields with the feature of high-sensitivity, light weight, fast response and low-cost, etc. However, the design of accelerometer is still using the traditional method, the mechanical structure and IC are designed independently. So it has a long cycle of research and design, high cost and can’t effectively analyze the complete performance of the system. Macro model is the interface from device level simulation to system level simulation. Based on the macro model, construct system level model of complex mechanical structure and processing circuit are constructed to analyze the overall performance of the system. Studying the macro model technology of accelerometer is of great significance for improving the efficiency and quality of sensors and meeting the increasing market demand.The macro model of accelerometer was studied by the design of piezoresistive accelerometer in this thesis. Firstly, kinds of classical beams structure of piezoresistive accelerometer were analyzed, and the structure of high sensitivity and low lateral effect was chosen. The location and the number of the piezoresistance were determined by analyzed the stress cloud of quality-beam structure. And full Wheatstone bridge was constructed by aluminum wiring. According to this research,we completed the structure design, the landscape design and the fabrication process design, constructed the 3D model of the accelerometer.The mechanical simulation, electrical simulation, mechanical and electrical coupling simulation of the structure have been carried out to analyze the influence of beam parameters to sensitivity, natural frequency and lateral effect by IntelliSuite software. Based on the study result and design indexes, six kinds of optimization structure were designed. We selected the optimal one after simulation analysis and comparison.Impact test, modal analysis, time domain performance analysis and frequency domain performance analysis of the optimal structure have been carried on to study the range, extreme impact, modal characteristics, time constant, response time and bandwidth.According to the result of simulation analysis, the macro model of the piezoresistive accelerometer was extracted. Then it was described by Verilog-A language. System-level simulation model was built in Cadence software by connecting the macro model and amplification circuit.