单片集成压力传感器及弱信号处理电路的设计

Design of Monolithic Pressure Sensor and Weak Signal Processing Circuit

通过分析硅压敏电阻与晶向的关系,找到力敏电阻在硅膜片上的最佳位置。经测量,在10～400kPa范围内,压阻电桥的灵敏度约为0.36mV/kPa。提出一种由惠斯登电桥双端输出和双级放大器组成的电路结构,以对称的输入结构和全摆幅输出,解决了传感器输出小、易产生零点漂移的问题。用Cadence软件对电路进行模拟,在5V电源电压下,该放大电路的输出范围为0.036～4.953V,开环增益为110dB,CMRR为105.8dB,相位裕度为63.68°,可满足压力传感器的要求。

Optimal position of piezo-resistor on Si diaphragm was obtained by analyzing piezo-resistive theory.The sensitivity of piezoresistive bridge was measured to be about 0.36 mV/kPa in the pressure range from 10 kPa to 400 kPa.A circuit structure consisting of a Wheatstone bridge and a two-stage operational amplifier was proposed,which solved problems of small output and temperature drift of monolithic piezo-resistive pressure sensor with symmetrical input stages and rail-to-rail output.Simulation result showed that the amplifier circuit had an output swing between 0.036 V and 4.953 V,an open loop gain of 110 dB,a CMRR of 105.8 dB and a phase margin of 63.68° at 5 V power supply,satisfying the requirement of pressure sensors.