Design and optimization of 8 bit ALU using reversible logic

Conventional Complementary metal oxide semiconductor circuits (CMOS) dissipate energy in the form of bits of information. This dissipation of energy is in the form of power dissipation and plays a very important role as far as low power design is considered. Today, most digital circuits are being designed using Reversible Logic. Design based on Reversible Logic helps in reducing heat dissipation, allowing nearly energy free computation, allowing higher circuit densities and enabling better testing of faults. In this paper, a novel design for a Reversible 8-bit ALU is proposed. The 8-bit ALU is designed by cascading 1-bit ALUs. The two major units of a 1-bit ALU are the control unit and the adder unit. For the control unit, the Control Output Gate (COG) has been used and for the adder unit the Haghparast and Navi Gate (HNG) has been used. The most significant aspect of this paper is that as compared to other papers, this ALU design has reduced gate count, and transistor count. The propagation delay was found to be significantly lesser at a value of 5.52 ns when compared with the value of 8.29 ns for an existing design. Simulation and verification of the proposed design was performed using Cadence 180nm technology software tool.