Look-up table based I-V model for GaN HEMT devices for Microwave Applications

Abstract

In this work, a newly found innovative interposable lookup table based nonlinear empirical DC I-V model for GaN HEMT device has been formulated. Angelov and Yang's models have been taken as reference models to study the effects of bias (Vgs, Vds) dependent traps (gate lag and drain lag), self-healing, virtual gate formation, etc. on I-V characteristics functions and their inclusion into I-V equation functions of the proposed model. A new polynomial ratio function of Vds with its coefficients varying with Vgs has been formulated as a first function of the I-V model equation, to describe the transfer characteristics of the GaN HEMT. The obtained coefficients of the polynomial ratio function have been calculated by the curve fitting tool, are used to form a look-up table so that the I-V model is fast and accurate. Model verification has been done using 8 × 75 µm gate periphery and 0.25 µm gate length GaN HEMT of UMS foundry. The measured and modeled results of I-V characteristics as well as transfer characteristics are compared and found to be matched accurately with each other. Because of this, this model is more accurate and proficient in the representation of GaN HEMT I-V characteristics when compared to the Angelov DC I-V model. The proposed methodology can be used to model all GaN HEMT devices.Using the proposed nonlinear I-V equation, an empirical model has been generated in AWR MWO using an interpolable lookup table of coefficients varying with Vgs for the GaN HEMT of UMS, CREE and WIN foundry, which can be used for Computer-Aided Design (CAD) of RF circuits, etc.