High linearity and high power performance with barrier layer of sandwich structure and Al0.05GaN back barrier for X-band application

The high power and linearity performance of GaN-based HEMT for X-band application was achieved using the barrier layer of sandwich structure and Al0.05GaN back barrier. The AlGaN-sandwich-barrier can modulate polarization-graded field for more flat transconductance profile under the high drain bias. Only about 7.5% current collapse (CC) occurs for drain quiescent bias of 40 V. Due to the Al0.05GaN back barrier, the three-terminal off-state breakdown voltage (BVDS) of 260 V and a very small drain-induced barrier lowering (DIBL) of 2.7 mV V−1 is achieved. The AlGaN sandwich barrier combined with Al0.05GaN back barrier device exhibits a high current-gain cutoff frequency f T of 42 GHz@V DS = 10 V, and a high power-gain cutoff frequency f MAX of 130 GHz@V DS = 60 V. Load-pull measurement at 10 GHz revealed a saturated power density of 7.3 W mm−1 was achieved with an associated PAE of 29.2% and Gain of 10.6 dB. Two-tone measurement at 10 GHz showed an OIP3 of 38 dBm and a corresponding linearity figure-of-merit OIP3/P DC of 4.5 dB. These results demonstrate the great potential of AlGaN-sandwich -barrier/GaN/Al0.05GaN HEMTs as a very promising alternative to high power and high linearity X-band power amplifier.