A Class E Power Amplifier for ISO-14443A

This paper reports on the design and implementa- tion of a class E push-pull amplifier in order to increase the reading range of an ISO-14443A RFID system. With the aid of classical design formulas and some alterations due to parasitic and intrinsic capacitances, a working implementation was made that can provide the loop with an amplified modulated current wave. I. INTRODUCTION The use of Radio Frequency IDentifier (RFID) technology is (becoming) widespread in different areas of our society and it is employed in various applications like access control, logistics tracking and animal identification. One of the most popular amongst the RFID standards is ISO-14443. This stan- dard defines the physical characteristics, the radio frequency power and signal interface characteristics, the initialization and anti-collision specifications and the transmission protocol to which the identification cards, contactless integrated circuit cards or proximity cards should comply. The MIFARE card by NXP is by far the best known representative for this class of RFID cards. The working frequency is 13:56 MHz and most Commercial, off-the-shelf (COTS) readers are designed for a reading range of 10 cm. In order to extend this range, some alterations to the reader design can be made. A standard reader can be envisioned to be comprised of two main building blocks: the reader logic and the antenna. This paper focuses on a powerful amplifier to boost the signal in between the two building blocks as shown in Fig. 1. The authors focused on the antenna design in a separate publication (1). A combination of both amplifier and antenna improvements results in an extended reading range. Of course this distance is limited due to physical properties related to the characteristics of the power transfer technique, the working frequency, the components used in the design, and the like.