Design of Contactless D-Band MMIC-to-Waveguide Transition Based on Multilayer Waveguide and SiGe Technology

Journal article, 2026

A D-band transition from silicon–germanium (SiGe) monolithic microwave integrated circuit to waveguide (MMIC-WG) is proposed in this letter. The transition includes a slot etched in the chip’s ground plane and a two-stage step in a metal waveguide. The slot works as a launcher for contactless electromagnetic field coupling, fed by a shorted microstrip line, while the step is an impedance transformer. As the assembly requires splitting the waveguide along the H-plane, glide-symmetric holes in a multilayer waveguide (MLW) are introduced as an electromagnetic bandgap (EBG) structure to suppress leakage, different from metal pins used in an H-split rectangular waveguide (RWG). As a proof of concept, a back-to-back (B2B) transition is fabricated based on MLW technology with an additional H-split RWG design as a reference. Measurement results show the proposed transitions have 2-dB insertion loss, in good agreement with the simulation. In addition, packaged receivers are also presented to validate the feasibility of the proposed transitions for sub-THz system integration.