Performance analysis of AlGaN/GaN based HEMT for different gate structure (Normal gate and T-shaped gate)

Abstract

In this work, a normal rectangular gate AlGaN/GaN based High Electron Mobility Transistor with gate length of 150 nm and a T-shaped gate AlGaN/GaN High Electron Mobility Transistor with a gate foot print of 90 nm are designed and compared. DC and RF performance is observed for both the devices. It is shown that the DC parameters like drain current, transconductance are nearly same for both the devices. Coming to the RF performance, the maximum cut-off frequency of the normal gate HEMT is 24 GHz at the drain voltage of 20 V and the gate voltage of 2 V where as the maximum cut-off frequency of the T-shaped gate HEMT is 47 GHz at the same drain and gate voltage. For T-shaped HEMT, it is observed that maximum cutoff frequency is double of the normal gate HEMT. Maximum frequency of oscillation for normal gate HEMT is 95 GHz and for T-shaped gate HEMT it is 115 GHz at same drain and gate voltage i.e. 2 V and 20 V. At the operating frequency 5 GHz, the minimum noise figure of the normal gate HEMT is 0.13 dB. At the same operating frequency the minimum noise figure of the T-shaped gate HEMT is 0.05 dB. These results prove that the RF performance of a T-shaped gate HEMT is much better than a normal gate HEMT and the T-shaped gate HEMT is more preferable for high frequency operations like radar communication, satellite communication, wireless communication etc.