ANALYTICAL MODEL FOR THE TRANSCONDUCTANCE OF MICROWAVE Al{sub}mGa{sub}(1-m)N/GaN HEMTs INCLUDING NONLINEAR MACROSCOPIC POLARIZATION AND PARASITIC MESFET CONDUCTION

摘要

An improved nonlinear analytical model is presented for calculating the transconductance of AlGaN/GaN HEMTs. The model uses a polynomial dependence of the sheet carrier density on the position of the Fermi energy level, and is valid from subthreshold region to high conduction region. It also highlights the importance of including nonlinear macroscopic polarization in calculating the 2-DEG sheet carrier concentration at the AlGaN/GaN heterointerface. Current-voltage characteristics developed from the present model include the effects of field dependent mobility, velocity saturation, channel length modulation, and parasitic source and drain resistances. The model is extended to include the parasitic conduction through the AlGaN layer, which reduces the transconductance (gm) at high gate voltages. The present model is based on closed form expression and does not involve any fitting parameter or excessive computation. The results obtained are in good agreement with published experimental data.