Research And Design Of RF Transmitter In Visible Light Communication-Radio Frequency Identification Tag

RFID as a wireless communication technology,it can obtain information from the multiple target electronic tags and high-speed mobile electronic tags.In recent years,RFID technology has been widely used in logistics management,intelligent transportation,manufacturing and processing,information security,and public information services,due to its anti-interference ability,long life,large capacity,small size and other advantages.However,there are some drawbacks in the passive RFID technology,in order to activate the electronic tag,the reader need to send a high power RF signal.These radiation sources can produce a strong electromagnetic radiation,which can result in not only the electromagnetic pollution but also the potentially human body harm.For the issues raised above,a new passive RFID technology,using visible light communication(VLC)as downlink communication and RFID backscatter modulation as uplink communication,has been proposed in this thesis.This thesis realized the research and design of RF transmitter on the tag that based on the new technology,include backscatter modulation circuit,matching network and on-chip antenna(OCA)design.The thesis focuses on the basic theory of the antenna,analyzes the basic principle of the electromagnetic field,and discusses some of the key performance parameters of the antenna design.And the design of the OCA is accomplished by using the equivalent circuit model and HFSS software.Then,based on the research of impedance matching principle and the principle of modulation technology,the design of backscatter modulation circuit and matching network is expounded in detail.The whole circuit is simulated by Cadence,and the tag is realized by TSMC 0.18?m standard CMOS process.The on-chip antenna is a 4-circle planar helical antenna with the wire width of 16?m and wire spacing of 5?m.The performance of the on-chip antenna and the backscatter modulation circuit is tested.And the test results shown that the RFID tag can achieve a communication distance of 6mm when the RF output power of the reader is 20 dBm.Compared with other RFID tags,this tag can achieve longer communication distance under the same RF power,or achieve shorter distance at lower RF power.