Power distribution in a Josephson package environment

Abstract

An ac power supply designed to power 8K Josephson logic circuits has been tested in a package environment for the first time. The test was part of an experiment that utilized the essential package components for a Josephson computer. All accessible chip-level power signals had the predicted amplitude variation with frequency over the range 50-400 MHz when normal fabrication tolerances were taken into account. This power supply, with reduced loading to accommodate some lines with unexpectedly low critical currents, was used to power the logic circuits in a path representative of a critical path for a proposed prototype processor. A minimum cycle time of 3.7 ns was achieved.