Design and Optimization of Low Cost Booster-based HF RFID Cards

Abstract

Novel designs for HF RFID cards comprise an intermediate circuit between the main coil and chip, such that the chip is not physically connected to the coil on card which reduces costs of production, enhances the card's robustness against mechanical stress and improves communication capabilities. Based on the Bode-Fano limit, we carry out a theoretical analysis on the bandwidth capabilities of such types of cards and their derivatives. We verify these results through simulations and measurements of our own design, denoted as booster-based cards. An optimization method for the design parameters of the booster-based cards is presented and derived. Measurements on three booster-based card prototypes are carried out showing the various bandwidth and power capabilities of the cards. Additionally, a comparison between the performance of such type of cards with respect to the conventional ones is presented. Card measurements included a chip, highlighting various states of the chip and its non-linearity.