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S. Rizkalla, R. Prestros, C. Mecklenbräuker:
"Optimal Card Design for Non-Linear HF RFID Integrated Circuits with Guaranteed Standard-Compliance";
IEEE Access, Special section on Radio Frequency Identification and Security Techniques (2018), 1 - 14.

The current state-of-the-art design criteria for \textit{High Frequency} (HF) \textit{Radio Frequency IDentification} (RFID) cards with a carrier frequency of 13.56 MHz depend on the choice of a resonance frequency and a quality factor of the card. After investigations, we show that these values are a result of the \textit{Integrated Circuit} (IC)'s non-linear behavior and its dynamic range. For that purpose, we present our method to accurately calculate the IC's circuit model during loaded and unloaded states and identify the dynamic range where the IC is capable of achieving load modulation successfully for all basic bit rates (106 up to 848 kbit/s). The calculated IC's circuit model is simulated and compared to measurements showing a good alignment. We formulate a constrained minimization problem to calculate the optimum inductance value for the card's coil that renders a standard-compliant HF RFID card using the IC's circuit model, dynamic range and including all the card's parasitic elements and loading effects from the reader side. A prototype card is manufactured based on the algorithm's output where it passes the standardized tests and operates for all basic bit rates within the field intensity range from 1.5 to 7.5 A/m, as specified by the standard.

http://dx.doi.org/10.1109/ACCESS.2018.2867290