Design limitations for superconducting A/D converters

This paper reviews the principle of A/D conversion using superconducting quantum interference and describes the results obtained with this technique At an accuracy of four or six bits the design of such converters is straightforward. Higher accuracy requires careful consideration of numerous design constraints including critical current uncertainty, power supply regulation, turn-on-delay, signal line crosstalk, and the threshold curve critical points. The implications of these constraints are analyzed with respect to an example design for an 8-bit converter.