Nonlinear modelling of AlN/GaN HEMT accounting for self-biasing effect during RF step stress: analysis and hard-SOA

In this study, we investigate the non-linear (NL) behavior of AlN/GaN HEMT under gain compressiontechnologies when submitted to 10 GHz single-tone RF-step stress, crucial for millimeter-wave power application robustness. We evaluate AlN/GaN transistors, targeting high-power amplifiers with operating frequencies above 30 GHz. We present here an original method that includes, in a unique NL expression, the varying self-biasing effect caused by step-stress sequences. This methodology serves as a tool for comparative analysis across various technological variants and transistor geometries post RF stress. The step-stress are conducted on HEMT in transistor saturated mode and in diode configuration alone, to assess the physical origins and location of the critical SOA of these devices. We identify the mechanism of failure as stemming from the degradation of the Schottky gate when subjected to critical RF power levels, due to its constrained capacity to handle power signals exceeding 18 dBm. Furthermore, we highlight the remarkable RF robustness of this technology, achieving gain compression of around 10 dB without degradation.