Layout considerations for common-base amplifiers operating at 200 GHz

This paper presents layout-considerations for common-base amplifiers operating in the deep millimeter-wave region around 200 GHz. The effects of the parasitics for different layouts have been investigated, searching for the optimal performance in terms of gain and bandwidth of operation. Different layouts have been tested with the fabrication of two common-base amplifiers. The employed fabrication process is a 0.13 um SiGe BiCMOS technology with max oscillation frequency (f_max) of 450 GHz. The fabricated devices have been embedded into a balanced architecture, which guaranteed input and output matching, and high stability of the amplifier. The two designs had different values of parasitic inductance for the base-connection of the transistors. The engineered parasitics of the first design boosted the gain up to 27 dB and 23 dB at 160 GHz and 210 GHz, respectively; while the second design optimized for minimal parasitics showed a very broadband of operation ranging from 155 GHz to 215 GHz. Compared against the state of the art of SiGe common-base amplifiers operating at millimeter-waves, the presented layout considerations enabled the highest reported gain-bandwidth product.