High-precision Temperature Sensor Design For UHF RFID

Internet of Things(IOT) just means the combination of RFID(Radio Frequency Identification). This paper focuses on the design of a temperature sensor intended for UHF(Ultra high frequency) RFID tags. Main job as follows:This paper discusses the basic principle of sensing temperature, and then determines the framework of temperature sensor. The difficulties and keys of the high-accuracy CMOS temperature sensor are pointed out as the elimination of non-ideal effects in front-end sensing circuit and the design of ?-? modulator in ?-?ADC.After arranging the maximum allowable error in front-end sensing circuit and ?-?ADC, the paper analyses the sources of the non-ideal effects detailed. Basing on the analysis, Dynamic Element Matching?Current gain-inducting error Elimination Techniques ? Second-Order Curvature-Correction Techniques and Trimming are proposed pointedly. This paper also researches on a low power nested chopper amplifier, which has a good performance. This paper also builds a system model for the ?-?modulator in the back-end ?-?ADC, and thus make it clear of all the errors impacting the fully performance. By using Cascade ? Auto-zero and Chopper techniques, the error due to Finite Amplifier Gain and noise are all eliminated.All the parts of temperature sensor are simulated and verified using the Spectre tools based on SMIC 0.18?m CMOS technology, the results fulfilled the ±0.2? demanded accuracy perfectly. The whole circuits work at 1.8V supply voltage, power consumption is 29.5?W, conversion rate is 80 SPS.