A Novel Concept of using Double Threshold Voltage Coupling to Improve the linearity of AlGaN/GaN HEMTs for millimeter-wave applications

In this letter, we demonstrate an AlGaN/GaN HEMT fabricated by synthesizing recess and planar devices along the gate width and incorporating N
2
O plasma treatment to form an oxide layer at the gate electrode of the proposed HEMT. The transconductance curve of the fabricated device has a plateau region larger than 7 V, with a flattened response curve of fT/f
max
with respect to the gate bias voltage. At the operating frequency of 30 GHz, the maximum power-added efficiency (PAE) is 41%, the value of the power density (
$\mathrm{P}_{\mathrm{o}\mathrm{u}\mathrm{t}}$
is 5.3 W/mm, and the associated 1dB compression point
$(\mathrm{p}_{\mathrm{l}\mathrm{d}\mathrm{B}^{)}}$
is 28 dBm. The device presented in this article has excellent potential for millimeter-wave applications where high linearity is essential.