A Novel Area-Efficient Binary Adder

S. B. Furber and J. Liu

Abstract

A novel circuit for binary addition based on a parallel-prefix carry structure is presented. This circuit uses a recoding of the conventional carry kill and generate terms to yield a number of improvements over previous designs. In particular, a single circuit produces both the carry signals and the Sum, Sum + 1 data that is required for a carry selection circuit, supporting a range of possible implementations all of which have high performance, regular layout and good area-efficiency. The simple design also leads to good power-efficiency.
Binary adders based on this technique have been used in the ARM9TDMI, the ARM Piccolo DSP coprocessor, and the AMULET3 asynchronous ARM processor.