A new two-dimensional C-V model for prediction of maximum frequency of oscillation (fmax) of deep submicron AlGaN/GaN HEMT for microwave and millimeter wave applications

An analytical two-dimensional capacitance-voltage model for AlGaN/GaN high electron mobility transistor (HEMTs) is developed, which is valid from a linear to saturation region. The gate source and gate drain capacitances are calculated for 120 nm gate length including the effects of fringing field capacitances. We obtain a cut-off frequency (f_T) of 120 GHz and maximum frequency of oscillations (f_max) of 160 GHz. The model is very useful for microwave circuit design and analysis. Additionally, these devices allow a high operating voltage V_DS, which is demonstrated in the present analysis. These results show an excellent agreement when compared with the experimental data.