RSFQ logic arithmetic

Several ways to achieve local timing of Josephson-junction RSFQ (rapid single flux quantum) logic elements are proposed. Several examples of serial and parallel pipelined arithmetic blocks using various types of timing are suggested and their possible performance is discussed. Serial devices enable one to perform n-bit functions relatively slowly but using integrated circuits of a moderate integration scale, while parallel pipelined devices are more hardware-wasteful but promise extremely high productivity. The possible local and self-timing of RSFQ logic elements has been demonstrated, making it possible to construct digital blocks and complex devices operating at extremely high clock frequencies, limited only by logic delays of the RSFQ elements ( approximately 100 GHz for the present-day Nb technologies).<
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