Research And Implementation Of Monolithic CMOS UHF RFID Reader

The traditional and omnipresent barcode labels which have revolutionized the identification system many years ago are becoming more and more inadequate for limited data capability, line-of-sight requirement and faking facility. Since the cost of electric tag gradually approaches that of a barcode, the radio frequency identification technology is attracting comprehensive attention for its higher data rate, longer reading range and flexible coding system.Typical ultra-high frequency (UHF) radio frequency identification (RFID) system is composed of passive electric tag, reader and data processing device. Current reader transceiver which communicates with tag in electromagnetic wave for exchanging information is generally made up of discrete components or hybrid technology with higher material bill and power dissipation. With the development of process and the growth of demanding for low cost, power-efficient wireless terminals, the monolithic BiCMOS and CMOS UHF RFID readers have emerged in the past few years.This dissertation presents the implementation of single-chip CMOS UHF RFID reader ranged from system analysis, circuit design and prototype measurement.Firstly, system requirements for transmitter/receiver front-end of the presented I/Q direct conversion transceiver architecture, local oscillator generator and baseband strip are analyzed and proven by system simulator in accordance with EPC C1G2, ETSI 302 208-1 and local UHF RFID regulations .Secondly, a compact receiver front-end composed of trans-conductor, passive switching stage and output trans-impedance stage is proposed in terms of stringent linearity and noise figure while listen/talk mode and dense reader environment requirements are considered. It is different with the traditional trade-off focusing on noise or linearity for listen or normal mode. It achieves 27dB/36dB noise figure in listen/normal mode and input-refered third-order intercept point of 13dBm:Thirdly, an optimized fractional-N frequency synthesizer based on low phase noise voltage-controlled oscillator using low dropout regulator and LC filtration technique and 3-order 3-bit programmable zero configuration sigma-delta modulator is described for better in-band and out-of-band phase noise performance. The measurement results affirm the validity of these techniques. The spot phase noise is about -92dBc/Hz and -125dBc/Hz at 200kHz and 1MHz offset from operation frequency. The RMS jitter and residual FM is lower than 6.7pS and 4.5kHz respectively. Fourthly, in order to deal with power requirement in accordance with UHF RFID systems for passive backscattering modulation mechanism, a flexible transmitter front-end supporting DSB-ASK, SSB-ASK and PR-ASK is presented for the DC-coupling zero-IF transceiver.Fifthly, a highly reconfigurable receive analog baseband with 0.3-1.3MHz variable bandwidth is implemented in terms of data rate and attenuation requirement. A feedback DC-offset removal circuit is included for alleviating the influence of the down-converted self-jammer and shortening setting-up time of signal chain. The 5kHz corner frequency fulfils the receive baseband setting-up time and output SNR simultaneously.Finally, based on aforementioned system specifications, circuit solutions and design techniques, a fully integrated UHF RFID transceiver is demonstrated in IBM 0.18μm CMOS process including all physical layer components and occupying a whole area of 4×4mm~2 .The complete measurement platform consists of field-programmable gate array (Xilinx Virtex-4 xc4vx35) and some discrete components like power amplifier and circulator. The output spectrum for DSB-ASK with Tari=25uS satisfies the transmission mask under dense reader environment. The receiver sensitivity is better than -65dBm in the presence of -4.4dBm in-band self-jammer while drawing 177mA from 3.3V power supply.This dissertation's work is supported by Shanghai Science and Technology Committee under project "Research of Critical Techniques in Portable UHF RFID Reader Receiver Front-end" (07SA04).