The Fundamental Research On Micro Gas Pressure Testing Instrument Based On SOC Technology

Micro gas pressure sensors are widely used in the fields of chemical industry, spaceflight, foodstuff processing, semi-conductor processing, electronic encapsulation and scientific researches. With the rapid development of MEMS and IC technology, integrating the pressure sensor with its signal processing circuits on the same chip is possible, and becomes a research focus all around the world.The fundamental research on micro gas pressure sensor based on SOC (System on a Chip) technology is implemented in this paper. A micro gas pressure testing instrument based on isolated IC chips is developed. It mainly consists of a micro gas pressure sensor, MCU and display component. The micro gas pressure sensor designed in this thesis can be fabricated using an IC compatible process, and it is composed of a heating resistor, a sensitive element and a testing resistor. The constant power heating circuit is designed to excite the heating resistor. The IC temperature sensor AD590 works as the sensitive element. While gas pressure varies in a specified range, thermal energy transferred through gas from the heating resistor to AD590 will change, which results in the temperature variation of AD590. Therefore, the gas pressure can be measured by monitoring the temperature of AD590. Considering the functional and low-power requirement of the system, the signal processing circuit is designed based on a signal processing chip INA114, and a MSP430F135 single-chip computer is used to control the whole process, including converting the analog signals into digital signals and displaying the measured results. Furthermore, in order to display and analyze the measured results more intuitionisticly and real-timely, a program realizing the communication between the instrument and other computers is written in LabVIEW language.This paper develops a micro gas pressure testing instrument with isolated chips, and realizes the measurement of micro gas pressure, which provides the foundation of realizing the single-chip micro gas pressure sensor ultimately.