Improving the transconductance flatness of InAlN/GaN HEMT by modulating V_T along the gate width

Abstract

A modulated VT HEMT with improved gm flatness is demonstrated for high linearity application. The modulated VT HEMT was achieved by connecting two elements with different VT values in parallel along the gate width, realizing a flat resulting transfer curve, and the two different VT elements were fabricated by recessing part area of the barrier along the gate width under the gate region. The proposed HEMT shows a gate voltage swing as high as 5.4 V, a high drain current of approximately 2 A mm−1, and an fT/fmax of 63/125 GHz with a much flatter profile within the large gate voltage range.