High-Efficiency UHF RFID Energy Harvesting Design

Radio Frequency Identification(RFID)System identifies objects with the electromagnetic conversion theory,its' basic idea is automatic identification,storing and retrieving objects' information with the RFID tags.It has the advantages of faster reading speed,higher reliability and coding information,and so on.This paper aims at design and realization of some key circuits in RF/Analog front end based on the basic principle and architecture of UHF RFID,at the request of low power consumption and high efficiency.At last,the consideration of layout and the comparison of simulation are given.Firstly,the principle and composition of RFID are discussed,and the physical theory of RFID is introduced.This paper analyzes the architecture of the typical RFID tag and the function of each circuit,and focus on the design of the energy harvesting.Secondly,the key of the energy harvesting is the rectifier.The rectifiers are classified as Dickson rectifier and bridge difference rectifier.Dickson rectifier is divided into six circuits: the basic structure,NCP-1 structure,CTS charge pump structure,NCP-2 structure,self-offset structure and the native structure.The six structures is designed and simulated,The comparison result is that the performance of self-offset structure is higher,its' receiving sensitivity is-16 d Bm,the highest efficiency in the high power is 67%,the highest output voltage is 2.25 V,the highest charge current is 134 ?A and the average discharge current is 1.6 ?A.Thirdly,for low power applications,this paper designs a floating-gate rectifier,it has the advantages of lower input voltage,higher power conversion efficiency and the compatibility with standard CMOS process.First,the bridge differential rectifier is analyzed,the factors of input voltage and power consumption is discussed,and the compensation principle of the floating-gate rectifier and the effective threshold is analyzed,these theory supplies the design of the rectifier.Then,the grounding floating-gate rectifier and the last floating-gate rectifier were designed,because the disadvantage of these two structures are lower output voltage under the small energy and higher output voltage under the large energy,the new floating-gate rectifier is designed.A rectifier with low input voltage is designed after the analysis of the main rectifier,the floating rectifier,the coupling capacitance and the storage capacitor.The maximum of the power conversion efficiency is 77.1%,the receiving sensitivity is-18 d Bm when the output voltage is 1V,all results reach the request.Other circuits in the energy harvesting were designed.Firstly,the principle of the impedance matching between the chip and antenna is analyzed,and an L type impedance matching circuit is designed.Then,using the diode chain in parallel,the current-limiting circuit of the rectifier's input and output end is designed.Finally,the paper designs the layout of the energy harvesting and the RFID analog front-end,the layout simulations reach the request.