Balanced AlGaN/GaN HEMT cascode cells: design method for wideband distributed amplifiers

Abstract

A report is presented on the specific design of a GaN HEMT cascode cell demonstrating significant improvement for flip-chip distributed power amplifiers. The active device is a 8×50 µm AlGaN/GaN HEMT grown on SiC substrate. The GaN-based wafer integrating the active part is flip-chipped onto an AlN substrate via electrical and mechanical bumps. The cascode cell integrates matching elements for power optimisation of wideband distributed amplifiers up to their maximum frequency and for intrinsic power balance of the cascode cell. Additional resistors are integrated to ensure bias path and stability, this last one being decisive for the studied application.