惠斯通电桥温度传感器读出电路的研究与设计

温度传感器应用非常广泛,从工业生产温度监控到生活家电温度监测处处存在。基于铂电阻的惠斯通电桥温度传感器因其可测范围宽而被广泛应用。由于集成电路系统功能越来越丰富,对于温度传感器的读出电路如果输出数字表征量,系统可以简单读取即可得到被测物品或者环境的温度,大大简化了系统设计。本文利用开关电容放大器,将惠斯通电桥温度传感器输出的弱电压信号放大,然后经过Sigma Delta ADC和数字滤波器转换成数字信号,最后通过I2C输出16 bit的精确表征温度的数字信号。设计时先采用Matlab建模,得到sigma delta ADC的系数,然后采用SMIC 0.18μm工艺实现具体电路,芯片供电电源3.3 V。仿真结果表明,输出的数字信号能精确地表征绝对温度值。

Temperature sensors are widely used,ranging from industrial production temperature monitoring to household appliances temperature monitoring.Wheatstone bridge temperature sensor based on platinum resistance is widely used because of its wide measuring range.As the function of integrated circuit system is more and more abundant,if the readout circuit of temperature sensor outputs digital signal,the system can simply read the temperature of the object or environment to be measured,which greatly simplifies the system design.In this paper,a switched capacitor amplifier is used to amplify the weak voltage signal from Wheatstone bridge temperature sensor,and then converted into digital signal through sigma delta ADC and digital filter.Finally,a 16bit digitalized temperature signal is output by I2C.In the design,MATLAB is used to finish the system design and get the coefficient of sigma delta ADC.Then the real circuit based on SMIC 0.18um technology is realized with cadence software.The readout circuit adopts 3.3V power supply.The simulation results show that the output digital signal can accurately characterize the absolute temperature value.