Equivalent circuit model of millimeter-wave AlGaN/GaN HEMTs

A 2 × 50 AlGaN/GaN High Electron Mobility Transistor (HEMT) is designed and fabricated with 0.1 µm gate-length and 2 µm source-drain distance in the paper. The maximum frequency of oscillation (fmax) may reach 177 GHz. The small signal equivalent circuit model is obtained by using the open-short test structure and reverse cut-off method. A novel large signal model is constructed based on the SDD form. The new I-V and C-V expressions are proposed to complete nonlinear fitting accurately by contrasting the measure results of the GaN HEMT. The convergence of the model is good during the harmonic balance simulation. So this modeling method can be applied to millimeter-wave GaN HEMTs.