Modeling of Superconducting Passive Transmission Lines

Superconducting technologies are moving toward very large-scale integration (VLSI) of circuits. Passive transmission lines (PTLs) are used to quickly and efficiently propagate single flux quantum pulses between separated logic elements of these VLSI circuits. PTI,s are often insufficiently modeled to correspond to reality. Therefore, the PTL needs to be thoroughly studied to determine realistic propagation characteristics. A quasi-transverse magnetic (TM) formulation is used to study superconducting passive transmission lines. The ambient temperature and changes in penetration depth with frequency are taken into account when solving the electromagnetic fields of a PTL. Per-frequency transmission line parameters are extracted from the quasi-TM field solutions. The results show a very close correlation to TetraHenry, an existing 3D solver, at significantly reduced computational cost. The results also clearly show that PTL propagation characteristics are sensitive to frequency and temperature.