Time-Component Complexity of Two Approaches to Multioperand Binary Addition

Component and time complexity measures in terms of number of gates and gate delays, respectively, are derived for two multioperand adder structures: a tree of carry-save adders and a tree of carry-lookahead adders. The parameters of the complexity measures are operand length, number of operands, and maximum fanin to the gates. The analysis involves a constructive derivation of the complexity of carry-lookahead networks including optimization by removal of redundant paths. An alternate measure of component complexity, number of packages with a given number of pinouts, rather than number of gates, is also presented.