Comparison of second-harmonic matching of AlGaN/GaN HEMTs at K-band

This paper presents a comparative study of input and output second-harmonic matching applied to 0.25μm Al-GaN/GaN HEMTs on s.-i. SiC substrates. The study focuses on the technology's use at K-band, which is close to the maximum usable frequency for high-power amplifier design. Four power amplifier MMICs using different second-harmonic matching schemes are compared in terms of PAE and output power. The results show the relative improvement of power and efficiency that is gained by the inclusion of second-harmonic matching in the design but also the impact on the power/efficiency bandwidth.