A Ka-Band Watt-Level High-Efficiency Doherty Amplifier MMIC in 90-nm GaAs Technology

This letter presents a Ka-band watt-level high-efficiency Doherty power amplifier (DPA) monolithic microwave integrated circuit (MMIC) in 90-nm gallium arsenide (GaAs) pseudomorphic high-electron-mobility transistor (pHEMT) technology. To realize the high efficiency of DPA at 6-dB power back-off (PBO), a low-loss compact Doherty output network is proposed to directly combine the matching network and the load modulation network (LMN) into a compact network. Then, the peaking amplifier of DPA is an optimized design to guarantee a sufficient load modulation at the 6-dB PBO level. The proposed DPA exhibits a measured saturation output power in the range of 29.5–30 dBm, with a corresponding peak power-added efficiency (PAE) in the range of 35%–40% from 26.5 to 30.5 GHz. Moreover, the PAE at the 6-dB PBO level of the proposed DPA is in the range of 25%–30.2% from 26.5 to 30.5 GHz.