Best compromise between tele supply and modulated rate of back scattered signal in RFID system

Emerging applications of contact less smart card operating at 13.56 MHz like video transmission and ICAO e-passport need high data rates. This study focuses on the communication from the deported element (batteryless smartcard or transponder) to the reader. In order to limit the cost of the transponders, most of the time, smart cards are batteryless. The chip is connected to an antenna and is supplied by the power coming from the induced voltage of the coupled antennas. Designers have to deal with a compromise between best chip supply and best load modulation. The purpose of this paper is to present a new method to compute the best load to switch for a given power supply. For this supply, the best modulation degree of the back scattered signal will be reached. The theoretical results and the simulation results will be compared to measurements.