Digital Frontend Design Of MEMS Pressure Sensor Chip

With the rapid development of MEMS(Micro-Electro-Mechanical System)technology and integrated circuit technology,digital silicon-based MEMS pressure sensor chip is widely used due to the high precision,small size,low cost,high integration.The nonlinearity and temperature drift,clock accuracy are the main factors affecting the performance.Effective on-chip calibration algorithm for these problems are necessary to improve the accuracy of the pressure sensors.In this thesis,the digital front-end design of signal conditioning circuit for silicon piezoresistive MEMS pressure sensor is studied.The factors influencing the accuracy of pressure sensor are discussed and analyzed.Corresponding effective calibration algorithms are proposed to improve the clock accuracy,nonlinearity and temperature drift.The main research work includes:Firstly,the development of MEMS pressure sensor and the research status at home and abroad are introduced.The basic theory of piezoresistive sensor and the non-ideal factors that affect the performance of pressure sensor are discussed.The whole signal condition circuit structure of piezoresistive MEMS pressure sensor chip is presented.Secondly,the digital front-end modules in the system architecture are analyzed and designed.The hardware optimization of the digital post-processing decimation filter in the sigma-delta ADC is carried out.The common pressure calibration algorithms are analyzed and compared.An effective solution to calibrate the nonlinear and temperature drift are proposed.For the hardware realization of the digital algorithm,a method with reusing the multiplier and adder in different time phase is presented,in order to reduce the power and area consumption.Analyzing the analog oscillator used in the on-chip clock generator,a calibration algorithm with frequency count comparison and clock successive approximation is porposed.The algorithm can effectively suppress the affects of process vairations,and thus improve the clock accuracy.In addition,based on the analyzation of the analog interface of the customized EEPROM(Electrically Erasable Programmable Read-Only Memory),the compatible interface of the EEPROM is designed.In order to effectively complete the scheduling of each module,the FSM(Finite State Machine)module is designed.Finally,the reset module,clock generation and the interface are designed.Thirdly,the digital front-end modules in the system architecture are simulated.the simulation method,the platform and the simulation results are illuminated.At the same time,FPGA(Field-Programmable Gate Array)verification is done for the specified digital module.The chip with integrating clock calibration module and the EEPROM interface module is tested.The test results show that the clock frequency accuracy is improved from 30% to about 5% after using the clock calibration scheme proposed in this thesis,and the power consumption of the clock module after calibration is 12?A.This thesis presents the digital front end module design of signal condition circuit of silicon-based MEMS pressure sensor.The design,simulation,verification and some testing results are analyzed and illuminated.The research work is valuable for the realization of MEMS pressue sensor.