Fast addition using a new number system

A new approach is proposed for the design of high speed adders. Unlike the traditional approach here the attention is on the data format. It is shown that converting one of the operands to a specific type of ternary numbers, called signed digit number, makes the addition faster by eliminating the carry term. The problem with this approach is the need for data conversion from 2's complement to SD number format and the reverse. This approach is later modified and a procedure is presented that produces the sum term even without any data conversion and with no formal carry propagation. The trade off is, of course, addition of some extra logical operations and bit-pattern search operation.