AlN/GaN/AlGaN-on-Si HEMT Achieving 1.3 W/mm at 5 V for 5G FR2 Handsets

This Letter reports a double heterostructure (DH) AlN/GaN/AlGaN-on-Si HEMT, which has been proposed, for low voltage (LV, $\le 5$ V) RF operation. The proposed transistor shows excellent DC ( ${I}_{\textit {dmax}} =1.9$ A/mm, ${g}_{\textit {mmax}} =0.66$ S/mm) and RF small-signal characteristics ( ${f}_{T}$ / ${f}_{\textit {max}} =145$ /195 GHz). Continuous-wave (CW) load-pull measurements at 30 GHz yield ${P}_{\textit {sat}}$ of 0.6 (1.3) W/mm at V $_{\textit {ds}}$ of 3.5 (5) V, and peak power-added efficiency (PAE) of 43% (42%). To the best of the authors’ knowledge, the ${P}_{\textit {sat}}$ values are the highest reported for LV GaN-on-Si HEMTs in 5G FR2, despite the use of conventional alloyed contacts and a gate length ( ${L}_{g}$ ) of 120 nm. Furthermore, among published LV GaN-on-Si HEMTs, the proposed transistor achieves a desired combination of saturation velocity ( ${v} _{\textit {sat}}$ ) and knee voltage ( ${V}_{\textit {knee}}$ ), which are critical factors for LV power amplification. The results reflect the promising potential of the proposed heterostructure to achieve high transmit power in 5G FR2 handsets.