Subterahertz signal crosstalk in transmission line interconnects

A low-temperature electro-optic sampling system was implemented to study the crosstalk of picosecond pulses between on-chip microstrip interconnects. With a submillivolt sensitivity and a subpicosecond temporal response, this system has allowed noninvasive, nodal testing of superconducting Nb integrated circuits. We have characterized pulse propagation and the crosstalk arising from two microstrip waveguides crossing perpendicular to each other, with one signal line crossing above the other. These results provided direct feedback for improving computer simulations of superconducting electronic circuits, but they are representative of any high-speed interconnect in today’s very large scale integrated circuit technology.