Automated Josephson integrated circuit test system

An automated test system for complex superconductive integrated circuits has been developed. Its low-speed capability consists of 96 identical input/output (I/O) channels controlled by a PC-486 computer. Each channel is capable of driving currents and reading voltages at frequencies up to 40 kHz. Integrating this low-speed I/O capability with high-speed test equipment controlled over the IEEE bus allows measurements at frequencies up to the limits of the test equipment. The system can automatically set biases, display I-V curves, measure parameter margins, plot threshold curves, extract experimental circuit values, and collect statistical data on parameter spreads and error rates. Issues of noise suppression, ground loop handling, and autocalibration are discussed.>