A Temperature Sensor with Ultra-High Accuracy for RFID Tags
Tian Wenzhuo · Computer and Digital Engineering · 2013
This paper describes an ultra-high accuracy CMOS temperature sensor intended for RFID applications,which is implemented in SMIC 0.18μm CMOS process.Instead of using any bipolar transistor,the proportion to absolute temperature(PTAT) current generator is based on sub-threshold MOS operation.A current-controlled oscillator(CCO) can be utilized to transform the PTAT current into temperature-dependent clock signal which is converted into digital signals by a counter.Through the optimization of the design of the current source and comparator,the sensor achieves a sensing inaccuracy of-0.1/+0.3℃ over operating temperature range from-20℃ to 50℃,which consumes less than 50μA from a 1.8V supply.