A Three-Stage 18.5-24-GHz GaN-on-SiC 4 W 40% Efficient MMIC PA

This paper presents the design and measured continuous-wave (CW) performance of a three-stage $K$ -band monolithic microwave integrated circuit (MMIC) power amplifier (PA) implemented in a 150-nm GaN-on-SiC process. The transistor peripheries are staged at a ratio of 1:2:8, and the output stage consists of two reactively combined $8 \times 100~\mu \text{m}$ HEMTs with individual source vias. The measured peak output power is greater than 4 W with peak power added efficiency (PAE) of greater than 40%. The output power exceeds 3.2 W over the frequency range of 18–24 GHz with less than 1.5-dB variation. The three-stage architecture enables greater than 20 dB of saturated gain from 18.5 to 24 GHz. The bandwidth, output power, and efficiency performance are investigated as a function of output stage drain voltage. A statistical analysis for 230 die fabricated on five wafers is presented, and eight MMICs are mounted and characterized over power and frequency.