Design and Optimization of an SSPP ‐Matched GaN HEMT Power Amplifier Using Bayesian Optimization

This paper presents a data‐driven methodology for designing a highly efficient power amplifier (PA) incorporating spoof surface plasmon polariton (SSPP) based matching networks. The PA employs a CG2H40010F GaN HEMT transistor and is optimized to operate across 3.0–4.8 GHz. Log‐periodic line (LPL)‐based SSPP unit cells are utilized in both the input and output matching networks to achieve enhanced field confinement and circuit miniaturization. A two‐stage design approach is adopted: initial optimization is performed through harmonic balance simulations using simplified real frequency technique (SRFT), followed by electromagnetic (EM) co‐simulation to capture full‐wave effects. A Bayesian Optimization framework is applied to systematically tune the SSPP geometrical parameters and LPL configurations, using output power ( P out ), power‐added efficiency (PAE), and gain as optimization objectives. The final design demonstrates a peak P out of 43 dBm, a drain efficiency exceeding 80%, and a gain of 13.6 dB. The proposed approach enables an efficient and compact SSPP‐based PA design without requiring hardware measurements, offering a promising direction for future wideband front‐end amplifier solutions.