Design and testing of quasi-one junction SQUID-based comparators at low and high speed for superconductive flash A/D convertors

The fabrication and testing of single comparators at low and high speeds (up to 10-GHz input bandwidth) to determine basic functionality, dynamic range, linearity, noise level, and dynamic distortions are described. A 4-b converter was tested at low speed without errors. The results indicate that a 6-b converter may be constructed of these comparators with very good linearity and 8 b should be achievable with slight design modification. The comparator was demonstrated to have an aperture uncertainty >