The Design And Realization On Mixed-signal Process Circuit For Pressure Sensor

Pressure sensors are broadly applied in many fields. The development and the application silicon piezoresistive pressure sensor based on MEMS technology are paid attention by the industry. The small, integrated and intelligent for the pressure sensors are the main trend.The design and the implementation on mixed-signal circuit for pressure sensor are accomplished for the company in the thesis. Silicon piezoresistive pressure sensors are applied to obtain the pressure signal. The power modules are rationally designed to ensure the stability of the output signal. The instrumentation amplifiers are composed of the classic three op amp approach, to amplify analog signal and signal normalization.2 different ranges of sensors are designed to ensure the accuracy in different test range. The second-order active filter circuits are applied to suppress the noise. Based on the systematic analysis, the AVR microcontrollers are selected as the system core. The analog signals are sampled and processed with the AVR microcontrollers, processing, to control the output switch. The digital filter technology is adopted to ensure the switch threshold range. The host computer communication software is designed with the VC software. the switch settings are realized using the RS-232 communication.After the software and the hardware debug, the design circuit out for the analog output is 0.5-4.8V, the ripple is less than 20mV,5 way switch can be controlled, and the pressue threshold is 20Kpa. The designed circuits achieve the desired targets.