Erich Merlin

Automatic impedance matching for 13.56 MHz NFC antennas

This paper deals with the concept, the implementation and the verification of an automatic impedance matching circuit for NFC antennas with a frequency of 13.56 MHz. Besides an introduction to manual tuning and its issues, the fundamental components of an automatic tuning system are outlined. A lab-scaled prototype is built and demonstrated. In the end, the successful operation of this system is tested with several different antennas.

Properties of a test bench to verify standard compliance of proximity transponders

Applications for public transport, electronic government or electronic banking based on ISO/IEC 14443, the standard for 13.56 MHz proximity contactless chip technology, require a huge number of integrated transponder chips, which up to now already exceeds 3 billion samples out in the field all over the world. It is a specific attribute of the passive RFID technology, that supply power, command reception and information transmission for the transponder chip is connected to one air interface. This requires to vary and test all parameters in combination, to be able to cover the real application case. We present a modular test bench allowing to combine higher layer protocol tests with analogue parameter variation in the contactless antenna arrangement as specified in the ISO/IEC 10373-6 test standard. As the HF near field technology cannot be covered just by relaxed UHF test methods but provides different and specific challenges, we focus on the specified antenna arrangement and explain in detail some of the properties and measurement concepts.

Active load modulation for contactless near-field communication

To integrate NFC functionality in Smartphones and mobile, personal devices requires small loop antennas and specific constructions. For card mode operation there is a physical limit for the minimum antenna size to achieve standard conformance with conventional, passive load modulation. Active load modulation (ALM) can overcome this limitation and allows to construct very small antennas, but other problems arise to fit into existing infrastructure. We consider NFC antennas and present a new ALM concept in construction and function, which can overcome these problems, and we present first comparative results for the performance gain.

Broadband NFC - A system analysis for the uplink

Near field communication (NFC) is a new, short-range wireless connectivity technology that evolved from a combination of existing contactless identification and interconnection technologies. Products with built-in NFC will have the aim to simplify the way consumer devices interact with one another. Data-intensive applications based on NFC or applications for health care/e-government need an increase from the actual defined and standardised transmission rates of 424 kbit/s to a higher rate. The topic of this paper is to point out physical layer parameters, limitations and concepts, allowing to enhance the transmission rate of the 13.56 MHz NFC-systems. Finally one implementation of a lab scaled prototype with a transmission rate of 6.78 Mbit/s from card to reader is demonstrated and discussed.

Extending the analogue performance of integrated 13.56 MHz proximity reader chips

SummaryWe demonstrate a practical concept to extend the performance at the air interface of RFID proximity readers using integrated reader chips. Our solution consists of an external, discrete circuit and we consider the transmit path as well as the receive path. We discuss important aspects for design and evaluate the quality improvement for a specific reader in some relevant characterization measurements.ZusammenfassungDie Autoren zeigen ein praktisches Konzept zur Verbesserung der Leistungsfähigkeit von RFID Proximity Readern an der Luftschnittstelle. Die Lösung besteht aus einer diskreten Schaltung zur Erweiterung integrierter Reader Chips, mit der die Ausgangsleistung im Sendezweig gesteigert und die Empfindlichkeit im Empfangszweig erhöht wird. Weiters werden wesentliche Aspekte für das Design betrachtet und der Qualitätsgewinn anhand relevanter Charakterisierungs-Messungen für einen Reader deutlich gemacht.