Advances on GaN based switch mode amplifiers for communication applications

This paper presents the design and implementation of a switch mode power amplifier as a building block for a purely digital transmitter chain for communication applications using high-power Gallium Nitride (GaN) monolithic microwave integrated circuits (MMICs) with high electronic mobility transistors (HEMTs). For square-wave excitation the measured output power and drain efficiency are 5 W and 64 %, respectively, enabling a highly efficient transmit chain. For evaluation purposes the amplifier has also been driven by a bandpass delta-sigma modulator (BDSM). In case of a 900 MHz continuous wave (CW) signal, the measured output power and drain efficiency are 2.3 W and 42 %, respectively.