A clear-cut understanding of the current-gain peak in HEMTs: Theory and experiments

The aim of this article is to provide a clear-cut understanding of the origin of the current-gain peak (CGP) affecting the microwave behavior of high electron mobility transistors (HEMTs). This effect consists of a sudden increase of the magnitude of the short circuit current-gain at a given value of the frequency. The present study demonstrates that the CGP can be attributed to the resonance associated to the transition from a capacitive to an inductive behavior of the open circuit output impedance, as confirmed through an extensive experimental analysis. In particular, the CGP is analyzed in HEMT devices based on both GaAs and GaN technologies and its appearance is investigated with respect to the gate width, bias condition, and ambient temperature. (c) 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:28012806, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27192