Improved Linearity Performance at High Operation Voltage on Dual-threshold Coupling AlGaN/GaN HEMTs by Modulating the Duty Ratio

In this work, high linearity AlGaN/GaN HEMTs accomplished by implementing the dual-threshold coupling technique (DT HEMTs) have been studied. It was found that the transconductance (G
m
) profile for DT HEMTs at high operation voltage was sever compressed induced by the high electric field (E-field), and the phenomenon could be optimized by modulating the α, which was defined as the duty ratio of planar- and recess-elements in a period width. Consequently, the fabricated composite device with α = 0.7 yielded the gate voltage swing (GVS-G
m
) of 4.5 V at V
ds
= 6 V, while GVS-G
m
of 3.97 V at V
ds
= 25 V was obtained by DT HEMTs whose α is 0.5. Meanwhile, For the DT HEMTs with α = 0.5, the predicted output third-order intercept (OIP
3
) of 39 dBm among a wide gate voltage range at V
ds
= 25 V was achieved, and the large signal performance at 8 GHz delivered P
out
of 4.7 W/mm with 1.9 dB improvement in gain compression (G
com
), and 2 dB enhancement in 1-dB compression point (P
1-dB
), respectively, at V
ds
= 25V. The suppressed G
com
and enhanced P
1-dB
indicates that the DT HEMTs with α = 0.5 is capable for linearity requirements at high operation voltage.