Transmission of high speed electrical signals in a Josephson package

It is proposed that Josephson circuit chips are housed in a three-dimensional, card-on-board package operated near 4.2K. In this technology logic signals travel on matched, low-loss, superconducting transmission lines and through low resistance but inductive package connectors. In an experiment designed to model closely the electrical environment of this package, the waveform of a Josephson driver signal was measured before and after propagation through a card-to-card path in the package. The measurements were made on-chip using Josephson sampling techniques. The degradation in risetime of a 125ps driver signal was less than 20ps; crosstalk to a parallel path through the package was less than 2%. The inductances of right angle and pluggable micropin connectors were determined using an impedance current split experiment. Measured values of about 100pH and 250pH respectively are in good agreement with numerical calculations.