Extraction of parasitics in GaN HEMTs via Full-Wave Electromagnetic Modeling

We present a new equivalent circuit model for millimeter-wave and sub-millimeter wave GaN high electron mobility transistors (HEMTs) that can capture the geometry-and material-dependent parasitic effects within the device. The impact of electromagnetic interactions on overall device performance is analyzed extensively via full-wave EM simulations using high-fidelity device geometries. An empirical lumped-element equivalent circuit model is developed to capture the electromagnetic behavior not only within the internal structure of the device but also the surrounding impedance environment. Based on this parasitic-aware equivalent circuit, a multiple-step parameter extraction algorithm is employed to determine the equivalent lumped elements. Numerical results, using a conventional sub-mmW HEMT topology are presented to illustrate the performance of the proposed circuit models in capturing device physics in the THz band.