Polysilicon Pressure Sensor Analog-to-digital Conversion Circuit Design

Pressure sensor has a key role in many fields.According to some literatures concerned, there are many kinds of pressure sensors, most of them are made from silicon wafer.In this paper, the pressure sensor is based on MEMS technology ,making four polysilicon resistances on the monocrystalline silicon.They make up of Wheatstone bridge,so we have the polysilicon pressure sensor Considering piezoresistance effect of semiconductor, when the pressure is applied on the surface of polysilicon pressure sensor,two polysilicon resistances turn to bigger, the other two resistances become smaller,so the Wheatstone bridge is out of balance, there is a output of voltage,finally we can convert the pressure signals to the voltage signals.This paper describes the structure and design of pressure sensor, work theory of pressure sensor, simulation and fabrication process of ADC circuit.The I-V characteristic, static properties and the temperature characteristic are tested.Then we have a simulation of testing signal circuit, ADC, control display circuit and circuit of power by software. In some degree the pressure sensor in this paper overcome disadvantage which poly silicon pressure sensors and enhance the stability of the sensor.ADC circuit reaches demand of design by experiment.