1–8 GHz high efficiency single stage travelling wave power amplifier

In this paper a Class-A/AB operated wideband power amplifier is presented that comprises of only a single transistor travelling wave stage where capacitive coupling and frequency dependent lossy artificial transmission-line are employed at the input of the active device. These technique are shown to significantly enhance the amplifier frequency-bandwidth product, input match and gain flatness performance over 1-to-8 GHz operating bandwidth. Furthermore, a non-terminated output artificial transmission line inductance is determined using load-pull data to achieve an optimum power-bandwidth performance. Overall 1.31×2.93mm² power amplifier design is fabricated by using 0.25μm GaAs PHEMT MMIC process and the amplifier delivers 1W and 0.5W peak P_sat and P_{out, 1dB} levels respectively where the PAE levels are over 50% and 27% for P_sat, and P_{out, 1dB} almost the entire 2-to-8 GHz frequency band.