The Improvement And Optimization Design Of Passive UHF RFID Tag

The Ultra High Frequency Radio Frequency Identification (UHF RFID) technology has become the focus of RFID technology now ,because of its advantages such as long reading distance,high Identifying speed,good anti-collision capability, and low manufacturing cost and so on.It has been regarded as the most promising and valuable auto identification technology.This paper mainly analyzes the UHF RFID technology of the frequency band of 860~960MHz, the working frequency of the passive UHF RFID tag system that is analyzed and designed in this paper is 915MHz.The improvement and optimization circuits design and layout drawing of bias,oscillator,power-on reset, modulator and other major modules of RF and analog front-end in the passive UHF RFID tag is implemented in SMIC 0.18μm 2P4M CMOS process.Considering the low-power consumption design requirement of the UHF RFID tag chip, the circuits design of RF and analog front-end are innovatively in low-power consumption means, for example, subthreshold CMOS PTAT current source and zero static power consumption start circuit structure is used in reference circuit, and power-on reset circuit has achieved zero static power consumption. the simulation results show that the total current consumption of the RF and analog front-end is only 2.4μA, which meets the low-power consumption requirement of the RFID system.Considering the clock signal in the UHF RFID tag chip is susceptible to temperature and supply voltage, it causes the system instability, the analysis of the stability of the oscillator in the tag is innovatively proposed in this paper from the perspective of bias circuit design,it illustrates how to make the output frequency of the oscillator independent of temperature and supply voltage and other factors, to improve the stability and accuracy of the RFID tag chip.The design of A new CMOS temperature sensor that can be integrated in the passive UHF RFID tag is proposed innovatively. The CMOS temperature sensor that is designed in this paper has so many advantages,the simple circuit structure,the small occupied chip area,the low-power consumption,and higher resolution and sensitivity, good temperature characteristic.And it can achieve the temperature tag function.