Background Accurately modeling gallium nitride high electron mobility transistors (GaN HEMTs) is essential for advancing solid-state high-power microwave systems. However, conventional parameter extraction methods often suffer from low efficiency and insufficient accuracy due to the complex physical layout of GaN devices. From an engineering application perspective, small-signal model parameter extraction must adhere to three core principles: accuracy, efficiency, and rapid verifiability.
Purpose This paper aims to present a rapid development method for small-signal equivalent-circuit models based on the physical layout of GaN devices, addressing the challenges in efficient and accurate parameter extraction.
Methods A small-signal equivalent-circuit topology containing 28 elements was constructed by analyzing the structural characteristics of the GaN device. Leveraging specific physical layout information and electromagnetic simulation results, a direct extraction method for extrinsic parasitic capacitances was introduced. Furthermore, a complete parameter extraction flow for the small-signal model was established using the Advanced Design System (ADS) simulation platform to enable fast parameter acquisition and efficient validation.
Results For a 4×375 μm GaN HEMT fabricated with a 0.35 μm GaN process, a corresponding small-signal equivalent-circuit model was developed, with both extrinsic parasitic and intrinsic parameters successfully extracted. Under the bias condition of \mathrmI_\textdsq =75 mA@ \mathrmV_\textds =60 V, the simulated S-parameters of the small-signal model showed good agreement with measured data across the 1～12 GHz frequency range, achieving an error of only 0.531%.
Conclusions Experimental results verify the effectiveness and practicality of the proposed method. The established extraction flow significantly improves modeling efficiency and accuracy, providing a reliable solution for the design and optimization of GaN HEMT-based high-power microwave circuits.
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