Thermal-Aware Co-Design of GaN-Based Power Amplifiers for High-Linearity 6G Sub-THz Transceivers

Abstract

The realization of high-linearity power amplifiers (PAs) at sub-terahertz frequencies is a critical challenge for emerging 6G transceivers, where extreme power density and wideband modulation exacerbate self-heating effects in GaN devices. Elevated junction temperature significantly degrades carrier mobility, shifts threshold voltage, and intensifies nonlinear distortion, resulting in gain compression and intermodulation distortion (IMD) deterioration. Despite advancements in GaN PA design, existing approaches largely optimize electrical performance without explicitly integrating electro-thermal coupling into linearity-aware design frameworks. This work presents a comprehensive thermal-aware co-design methodology that combines temperature-dependent large-signal modeling, dynamic electro-thermal coupling, and thermal-constrained load-pull optimization. Structural heat-spreading strategies and temperature-compensated bias stabilization are incorporated to mitigate thermal-induced nonlinearities. At 140 GHz, the proposed approach demonstrates substantial IMD3 suppression, improved power-added efficiency (PAE), and stabilized junction temperature under elevated ambient conditions. The results confirm that integrated electro-thermal optimization is essential for achieving robust, high-linearity GaN PAs suitable for next-generation 6G sub-THz front-end architectures.