The design of a high efficiency Class-F power amplifier using GaN technology

Abstract

Power amplifiers are used in the final amplification stage of all wireless electronic communication systems to transmit information-bearing signals for a diverse range of applications. Power amplifiers are fundamentally power converters that convert direct current power to radio frequency power. The fraction of direct current power that is not converted to radio frequency power is dissipated as heat within the power amplifier. This phenomenon is described by the power conversion efficiency, and power added efficiency. A CubeSat is a very small satellite, which must conform to specific standardised criteria that allocate constraints on factors such as the size, shape, and weight of the CubeSat and its components. CubeSats are battery operated and have limited available direct current power. This constraint warrants extensive investigation to minimize the direct current power consumption. One of the methods to achieve this minimising of direct current power consumption on the CubeSat is by maximizing the efficiency of one of the components, which is the power amplifier, that wastes much of this precious resource. To achieve maximum power efficiency a review into power amplifier classes and their respective operations were performed. A power amplifier operated in Class-F mode is a suitable candidate to achieve high power efficiency and thus further investigation and analysis was conducted into this power amplifier class and mode of operation. The design of a Class-F power amplifier is presented in this thesis. The power amplifier uses the GaN HEMT CGH40010F active device from Cree/Wolfspeed. A special output network, connected to the drain of the active device, was designed to achieve high efficiency. This Class-F power amplifier achieved a power efficiency, power added efficiency, and output power of 82.16 %, 72.4 %, and 40.06 dBm respectively, at a frequency of 2.1 GHz.