一种面向无源RFID系统的温度传感器设计

Design of Temperature Sensor for Passive RFID System

针对无源RFID系统的应用需求,设计了一款高精度片上集成温度传感器电路芯片。提出了一种由温度感应电路、PTAT偏置电流产生电路和Sigma-Delta ADC共同组成的温度传感器电路架构。采用基于双极晶体管的温度感应电路产生与温度成正比的电压,并采用Sigma-Delta ADC对其进行量化,得到与温度对应的数字量。在偏置电路中采用了斩波稳定技术,减小了由晶体管的失配及运放的失调引起的误差。在电流镜中采用了动态匹配技术,消除了由于电流镜失配引起的误差。采用GSMC 0.13μm CMOS工艺完成了对温度传感器的电路设计及版图绘制,版图面积为420μm×350μm。后仿真结果表示,在-40℃~+85℃的温度范围内,温度传感器的精度为-1.6℃/0.8℃,分辨率为0.75℃。在电源电压为1.5 V下,温度传感器消耗的电流为0.253 mA。

According to the application requirements of passive RFID system,a high precision integrated temperature sensor chip is designed.A temperature sensor circuit architecture composed of temperature sensing circuit,PTAT bias current generation circuit and Sigma-Delta ADC is presented.The temperature detection circuit based on bipolar transistor is used to generate the voltage which is direct proportional to the temperature,and Sigma-Delta ADC is used to alternately quantize the voltage to obtain the digital quantity corresponding to the temperature.Chopping stabilization technology is adopted in the bias circuit to reduce the error caused by transistor mismatch and operational amplifier offset.The dynamic matching technology is adopted in the current mirror to eliminate the error caused by the current mirror mismatch.The circuit design and layout drawing of the temperature sensor are completed by using GSMC 0.13μm process,and the layout area is 420μm×350μm.The post simulation results show that the accuracy of the temperature sensor is -1.6℃/0.8℃in the temperature range of -45℃~+85℃,and the resolution is 0.75℃.When the power supply voltage is 1.5 V,the current consumed by the temperature sensor is 0.253 mA.