A 47 % Fractional Bandwidth Sequential Power Amplifier with High Back-off Efficiency

This paper presents a 2.9-4.7 GHz sequential power amplifier (SPA) based on two 10 W GaN high electron mobility transistors (HEMTs). A wideband output combiner and input splitter which establish an optimal relative phase for achieving maximum efficiency are designed. The proposed SPA attains a bandwidth between 2.9 GHz and 4.7 GHz (47 % fractional bandwidth) with efficiency enhancement at output power back-off (OPBO). The measured results over the band of operation show a drain efficiency of 43 % - 56 % at a maximum output power of 40 dBm - 42 dBm, and of 36 % - 52 % at 6 dB OPBO.