A Quasi-Physical Compact Large-Signal Model for AlGaN/GaN HEMTs

Abstract

This paper presents an accurate quasi-physical compact large-signal model for GaN high electron mobility transistors (HEMTs). The drain current I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</sub> expression is acquired by combining the zone division method and the surface potential theory. The proposed I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</sub> model only contains 19 empirical parameters, with self-heating, ambient temperature and trapping effects considered. The self-heating effects are modeled by a polynomial function of temperature and gate voltage for the critical electric field E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> . And the ambient temperature effects are modeled by modifying pinchoff voltage and maximal electron saturated velocity. The trapping effects are considered with an effective gate-source voltage method. Moreover, taking the advantage of good physical meaning, the proposed I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</sub> model is scalable. In house 0.15-μm GaN HEMTs with different sizes are used to validate the model by dc I-V over a wide ambient temperature range, pulsed I-V, multibias S-parameters up to 50 GHz and multibias large-signal characteristics at f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> = 30 GHz. The good results show that the proposed quasiphysical zone division model is useful for millimeter-wave GaN HEMTs development and circuit design.