Passive Design and Optimization of an Interdigitated AlGaN/GaN HEMT for F-Band Slow-Wave Amplifier

This study explores the design of an interdigitated HEMT-based traveling-wave amplifier by studying the passive geometrical components. The HEMT is designed with an AI-GaN/GaN substrate stack to operate as a slow-wave structure. An interdigitated gate structure is implemented to generate a slow wave toward gain enhancement. The effects of the parametric variations in the grating region are investigated through passive simulations. Making appropriate modifications in the interdigitated region optimized the performance and provided the best responses in the 90–140 GHz band (F-band). The peak of the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$S_{11}$</tex> curve moves with the change in grating parameters and 42 gratings yielded the best outcomes. A low <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$S_{11}$</tex> of -44.5 dB and 98% power efficiency was observed in the F-Band for this model.