Resource sharing among mutually exclusive sum-of-product blocks for area reduction

In state-of-the-art digital designs, arithmetic blocks consume a major portion of the total area of the IC. The arithmetic sum-of-product (SOP) is the most widely used arithmetic block. Some of the examples of SOP are adder, subtractor, multiplier, multiply-accumulator (MAC), squarer, chain-of-adders, incrementor, decrementor, etc. In this article, we introduce a novel, area-efficient architecture to share different SOP blocks which are used in a mutually exclusive manner. We implement the core functions of the largest SOP only once and reuse different parts of the core subblocks for all other SOP operations with the help of multiplexers. This architecture can be used in the nontiming-critical paths of the design, to save significant amounts of area. Our experimental data shows that the proposed sharing-based architecture results in about 37% area savings compared to the results obtained from a commercially available best-in-class datapath synthesis tool. In addition, our proposed shared implementation consumes about 18% less power. These improvements were verified on placed-and-routed designs as well.