On-line multioperand addition based on on-line full adders

In this paper we deal with the online addition of multioperands for conventional, carry save (CS) and/or signed-digit (SD) numbers. We propose an online full adder (olFA) as the key element to design trees of adders to deal with multioperands. We also consider mixed inputs (e.g. SD and CS) and how to obtain the output in any of these representations. We show that for dealing with online multioperands it is more efficient to work with online CS trees based on olFAs than with online SD tree based on online SD adders. Finally a novel olFA-based architecture is proposed to directly deal with SD numbers.