Current polarity switching decoders for Josephson memory arrays

Two new types of Josephson decoder circuits have been devised, designed, fabricated, and tested. The circuits utilize current polarities along address loops as information. This results in simple circuit configurations with about half the number of circuit gates than conventional Josephson decoder circuits. This contributes to improved yield rates and to a decrease in circuit area. One of the two decoder circuitsz described in this paper can be operated with either dc or unipole while the other is unipole only. Using computer simulation, the operating speed for the former 5-32 decoder circuit is about 320 ps which is almost the same as that of conventional decoders, while for the latter circuit it is 115 ps which is almost half of that for the conventional decoders. The decoders are designed with operating margins of over ±35 percent which is sufficient for Josephson circuits. Critical path subsections of these two 5-32 decoder circuits were fabricated by standard lead-alloy technology and quasi-staticaUy operated successfully.