Wirelessly Programmable Class-E GaN-Based 13.56 MHz Transmitter for Wireless Power Transfer

This paper presents the complete design and im-plementation of a class-E Power Amplifier (PA) aimed to drive the transmitter coil in a centimeter-range wireless power link at 13.56 MHz. This kind of systems are prone to variations in the transmission distance, orientation, and could be affected by the presence of foreign conductive or ferromagnetic objects. These variations could change the class-E PA load impedance <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</tex> nd/or the power delivered to the receiver (Rx), Therefore, the proposed Class-E PA is able to: 1) control its output current in closed-loop to compensate for changes in its load, 2) protect itself against large changes in its load that could strongly affect the operating point increasing power dissipation, and 3) adjust its output current to the value requested by the Rx via Bluetooth Low Energy (BLE). Hence, this paper contributes by presenting not only the design of a comprehensive class-E PA transmitter from a system-level perspective but also addressing various practical aspects essential for actual implementation. Measurement results of the implemented prototype validate the proposed system architecture and its design.