Aiming at problem of limited communication distance of passive UHF RFID systems

a design scheme for new type of passive two-port intelligent tag is proposed. Realization method of intelligent selection and principle of improving system identification distance are expounded

structures of other parts of circuit

including rectifier

voltage regulator

modulator and demodulator are also given

the circuit is realized based on 0. 18 μm CMOS process. Simulation results show that each part of the circuit can work properly.