Integrating InP MMICs and Silicon Micromachined Waveguides for Sub-THz Systems

A novel co-designed transition from InP monolithic microwave integrated circuits to silicon micromachined waveguides is presented. The transition couples a microstrip line to a substrate waveguide sitting on top of a vertical waveguide. The silicon part of the transition consists of a top and a bottom chip, fabricated in a very low-loss silicon micromachined waveguide technology using silicon on insulator wafers. The transition has been designed, fabricated and characterized for $\mathrm {220~ \text {GHz}}~\text {to}~\mathrm {330~ \text {GHz}}$ in a back-to-back configuration. Measured insertion loss is $\mathrm {3~dB }~\text {to}~\mathrm {6~dB }$ at $\mathrm {250~ \text {GHz}}~\text {to}~\mathrm {300~ \text {GHz}}$ , and return loss is in excess of 5 dB.