Microstrip coupler circuits on micromachined silicon substrates for F-Band applications

Various microstrip coupler structures have been realized using high resistivity silicon on insulator (SOI) wafers. By applying an anisotropic etching process, membranes with a thickness of 50 mum are achieved. Thereby it is possible to realize low-loss microstrip circuits for millimeter-wave applications in F- band. This paper presents a side-coupled filter structure, a 10 dB directional coupler, a branch-line coupler, a rat-race coupler and a Wilkinson divider. The circuits are designed for the 122 GHz ISM band. The measured characteristics of the circuits agree well with the results achieved by momentum simulation.