The Research And Design Of Passive UHF RFID Tag With Temperature Sensor

RFID (Radio Frequency Identification) is a kind of non-contact identificationtechnology, it transfers data through radio frequency signal automatically, because ofits advantages such as waterproof, antimagnetic, high identifying speed, hightemperature resistant, long service life, long reading distance and so on. It has beenregarded as the most promising and valuable auto identification technology.This work presents the design of the analog frond-end (AFE) circuits for a UHFRFID tag in compliance with the ISO18000-6C protocol. The entire circuits havebeen processed with SMIC0.18μm2P4M CMOS process.Rectifier voltage regulator circuit includes a charge pump, a protection circuit anda voltage regulation circuit. In order to reduce the cost of the chip, NMOS transistorswith zero threshold voltage are used in the charge pump instead of the Schottky diode.The clamping voltage of the protection circuit is1.6V, the regulator can generated astable1.5V output voltage.The ASK demodulator employs a differentiator circuit, which extends the voltagerange of the input RF signal, solving the demodulating problem when the tag worksclose to a reader.This paper presents an ultra-low power CMOS temperature sensor architectureintegrated in passive UHF RFID tag. For deployment in applications of passive UHFRFID tag, power consumption is of utmost importance. In order to reduce the powerconsumption, a method of reusing current generated by the internal circuit of the tagis adopted and the clock signal is produced by the internal oscillator. It is realized inSMIC0.18μm2P4M CMOS process, the simulation results shows that increasedtemperature sensor module power consumption is only100nw at room temperatureunder supply voltage1.5V. The temperature sensor resolution is℃0.4/LSB in therange from-20℃to80℃.