Tapered transmission lines for terahertz systems

Complex terahertz (THz) System-on-Chip (TSoC) circuits require ultra-wideband low-loss low-dispersion interconnections between building-block components of various dimensions and characteristics. Tapered transmission lines, which enable the gradual transformation of both physical dimensions and characteristic impedance, are a convenient basis for these interconnections. In this paper, we quantify both experimentally and through simulation, the efficacy of transmission-line tapers connecting two different coplanar-strip transmission-line configurations, for frequencies up to 2.0 THz and with 25 GHz spectral resolution. We demonstrate tapers that enable transitioning from a small device-constrained transmission-line dimension (10 μm line width) to a lower-loss (20-40 μm line width) dimension, as a method to reduce the overall attenuation, and outline design constraints for tapered sections that have minimal detrimental impact on THz pulse propagation.