Redundant arithmetic, algorithms and implementations

Performance in many very-large-scale-integrated (VLSI) systems such as digital signal processing (DSP) chips, is predominantly determined by the speed of arithmetic modules like adders and multipliers. Even though redundant arithmetic algorithms produce signi"cant improvements in performance through the elimination of carry propagation, e$cient circuit implementations of these algorithms have been traditionally di$cult to obtain. This work presents a survey of circuit implementations of redundant arithmetic algorithms. The described implementations are divided into three main groups: (1) conventional binary logic circuits, which encode the multivalued digits of redundant arithmetic into two or more binary digital signals; (2) current-mode multiple-valued logic circuits, which directly represent multivalued redundant digits using non-binary digital current signals; and (3) heterostructure and quantum electronic circuits, intended for very compact designs capable of operating at extremely high speeds. For each of the circuits, the operating principle is described and the main advantages and disadvantages of the approach are discussed and compared. ( 2000 Published by Elsevier Science B.V.