A Pressure Transmitter Of High Accuracy Based On PGA309

Silicon piezoresistive sensors are widely used for pressure measure.Consistency, temperature shift and non-linearity are ubiquitous because of semiconductor's inherent characteristics.Compensation and calibration are needed for piezoresistive sensor's output voltage.In addition,the pressure sensor should be sometimes fixed near the testing,while the receiving device in long-distance,so the number and ullage of signal transmission line should be as far as possible few and it's antijamming ability as far as possible mang.Using the two-wire current transfer method,the power and signal transmission can be accomplished in a couple of lines,and the voltage decline caused by the long distance transmission,the noise caused by the motor,the switch and the industry equipment can be reduced.Based on studying traditional compensating technique,in virtue of the smart analog-digital-mixed signal conditioning technique,the smart error compensation is designed with PGA309 as its core.The issues of consistency,temperature shift and non-linearity are solved by the system which is composed of hardware and software.An output error factor of Silicon piezoresistive sensor is achieved within 0.2%.The main contents to be studied and solved are shown as follows:designing scheme of the error compensation system,studying and designing the signal conditioning circuit,designing and realizing the PGA309 software development system.The compensating circuit is designed in virtue of the signal conditioning chip PGA309 as its core.The 4～20mA current switching circuit is designed in virtue of the current switching chip XTR115 as its core.The PGA309 compensation system is developed by VC++,which can be used by all Windows operating systems,the computer's communication to the PGA309 and EEPROM has realized through the PC serial interface.The compensation process of PGA309 is automated ultimately and the operating surface is simple and friendly.The system is achieved by hardware and software debugging.Operating stabilization and credibility are approved by spot test.The analysis of a large amount of experimental datas proves that the system is feasible.