Millimetre‐wave on‐chip SIW filtering crossover using 0.25 µm GaAs pHEMT technology

This letter presents a novel millimetre‐wave (mm‐wave) on‐chip substrate integrated waveguide (SIW) filtering crossover using 0.25 µm GaAs pHEMT technology. The design methodology of the proposed crossover is thoroughly illustrated. The proposed filtering crossover employs a dual‐mode cavity with TE 102 and TE 201 degenerate mode resonances at the intersection, leveraging the degenerate modes for in‐band resonance and inter‐channel isolation. Additionally, four TE 101 mode resonant half‐mode SIW cavities are coupled around the dual‐mode cavity to achieve two third‐order bandpass response channels and reduce the overall size. A prototype is designed, analysed, and fabricated to validate the proposed approach, with measured results showing good agreement with simulations. The presented on‐chip SIW filtering crossover offers promising potential for mm‐wave applications, demonstrating the effectiveness of the design methodology and GaAs pHEMT technology integration.