Wide word‐length carry‐select adder design using ripple carry and carry look‐ahead method based hybrid 4‐bit carry generator

Abstract

Abstract This research aims to fill up the research gap in energy‐efficient transistor‐level wide word‐length carry circuit generator by using ripple carry (RC) and carry look‐ahead (CLA) method‐based hybrid 4‐bit carry generation process for wide word‐length carry‐select adder (CSLA). Compared to the existing 4‐bit CLA architectures, the proposed 4‐bit RC‐CLA method‐based hybrid 4‐bit carry generator showed performance improvement in terms of power and power delay product (PDP). Later, the 4‐bit carry architectures (existing and proposed) were used as a base to implement 16‐bit carry select adder (CSA) in order to investigate and compare the effect of using the proposed hybrid RC‐CLA based 4‐bit carry generator in large structures. Unlike 4‐bit operation, the proposed design displayed the best performance in power and PDP for 16‐bit CSA extension, which proves its effectiveness in wide word‐length adder structures.

Keywords

• 4‐bit adder
• adder
• carry select adder
• carry‐look ahead
• ripple carry adder