Simple Small-Signal HEMT Model Suitable for GaN Stability Analysis and Technologies Benchmarking

Abstract

This article deals with the extension of the small-signal model usage to GaN technologies benchmarking, and to the detection of internal oscillations occurring in highly optimized multi-finger GaN high-electron-mobility transistors (HEMTs). The proposed small-signal model consists of only 14 circuit elements. Its simple semi-analytical extraction procedure is developed in Keysight ADS circuit simulator, letting instantaneous comparison between modelled and simulated small-signal parameters. The simplicity and the adaptability of the technique always ensures a physical model parameter extraction. The technique is demonstrated for various technology processes, layouts, dimensions, and for three commercially available GaN vendors. The extracted data and the number of circuit elements are used to benchmark GaN technologies in terms of bias dependency, efficiency, and static linearity. By coupling the small-signal model to the electromagnetic (EM) GaN HEMT layout simulation results in a powerful tool for detecting odd-mode and even-mode instabilities. The technique is proven for various GaN basic cells as well as for power bars. Even prior to structure fabrication, the tool can be used to analyze its stability behavior by exploring its layout.