Analysis and Design of an X-band Stacked-FET Power Amplifier with Large Bandwidth

This paper proposes a broadband power amplifier (PA) based on stacked-FET structure. Compared with the traditional power amplifier in a parallel configuration, the proposed PA has relatively large equivalent output impedance, better output matching capability, and higher output power. For the same metric, stacked-FET PA can achieve reduced size and larger bandwidth, saving valuable chip area. This stacked-FET PA is fabricated using a 0.25 μm GaAs pHEMT process, and the simulation result shows that it achieves a saturated output power of more than 36.5 dBm, typically up to 37.2 dBm, with a maximum power-added efficiency (PAE) of more than 44% from 7.5 to 11.2 GHz.