Research And Design Of The RF Interface For 13.56MHz Reader Chip

RFID is a kind of wireless identification technology. Its initial usage was in a particular industrial conditions where bar code scout technology could not apply in, and at that time many enterprises and companies use it to orientate,confirm and scout stored products as well as other objects. RFID tag has many advantages which lie in noncontact, long distance reading, capable of identifying moving objects. A basic RFID system includes Reader and Tag. The circuit of the tag is very simple cause of the low cost. Thus the RF interface circuit of the reader chip should have better performance as well as higher stability. RF interface is one of the most significant techniques in the RFID chips.This paper systematically discusses the design process and key technique of the RF interface circuit of the reader chip. Firstly derivation and introduction basing on the electromagnetic wave system theory, the paper analyses the important technique of the reader RF interface, and provides useful solutions. Then, the system configuration is designed on the basis of RF protocol and performance requirement of the reader. Part of circuit modules are simulated in the system level and the parameter requirements in circuit level for each module are given. According to the new system configuration, quadrature demodulation sampling circuit, band filter circuit, adjustable amplifier circuit and pulse building circuit are designed and simulated in the transistor level.At last, using the CN1302 tag chip circuit, the simulation model of the whole RF interface is made. The verification methods and simulation results are presented at the end of the paper. The design has been implemented with 0.35um CMOS technology by SMIC . The RF interface design realizes the anticipation functions and fulfills the performance requirement of the international standard.