Research Of Passive UHF RFID Tag Chip And On Chip Temperature Sensor

Passive UHF RFID, which could automatically identify objects without contact, is one of the key technologies of The Internet of Things. Relative to the RFID which work at others frequency, the UHF RFID have some advantages:fast communication rate, long communication range and suit to objects with high velocity.Firstly, the constitute and the working principle of the UHF RFID system were simply introduced by this work, the transmission of the energy and data in forward and backward direction was introduced to. The conclusion that the power consumption of the tag chip is the most important restrict of the communication range was got by analysis and calculation.And then, a whole system scheme was proposed in this work, and the RF front-end, the analog front-end, the digital base-band and the memory were introduced. Specially, an all CMOS ultra-high efficiency, threshold compensate multiply and rectifier was proposed. The efficiency of the rectifier is no less than 50% during the possible input energy range. Through analysis and calculation, combine with the requirement of the memory, this work proposed the conclusion that the control voltage of the high voltage mos FET is the main restriction of the communication range. Based on this, this work proposed a regulator which has multiply function. The reading range of the tag was extended to 6.8m from 5.1m after adopted the proposed regulator.The application will be hugely extended when the RFID combined with sensor. Because of this, after the analysis of the difficulties of combining the traditional temperature sensor with the UHF RFID tag chip, this work proposed a new temperature sensor which is very suitable to the UHF RFID tag chip. The proposed temperature sensor adopted double oscillators, which made the sensor stronger. And the time divided model was used in the sensor, the communication range will not be shortened. The sensor worked during the time between the power up and the coming of the command.The test result showed that the maximum error was ±1.5 ℃ during -40℃ to 85℃.Considering the safety of the communication, this paper proposed two random generators. The first one used the heat noise of the resistor as the source, the noise was amplified by amplifier, and sampled by D-flip-flop. The amplifier adopted low power technology, and the power consumption of the entire random generator was only 800 nW. The another one used the clock jitter as the source of noise. The circuit was based on the proposed temperature sensor, and adopted time divided mode too.Finally, the proposed tag chips were implemented in SMIC 0.18μm EEPROM 2P4M process by multiply project wafer (MPW). The test was separated in two ways. Firstly, the tag chip was bonding on a printed circuit board (PCB), which connected the Reader using wire. The wave-forms were monitored by oscilloscope, and some wave-forms of key signals were given in the paper. And in the second way, the tag chip was bumping on the antenna, the testing environment was very closed to the real working environment. The results shows that the reading distance was more than 6.8m, and the writing distance was more than 1.8m, the average reading rate was 66 per second.