Design of Reversible Carry Skip Adder for Digital and Optical Circuits

In this paper, high speed carry skip adders for two different circuits were proposed. In the conventional structure of CSKA consists of a chain of ripple carry adder (RCA) block and 2:1 multiplexer. In the proposed structure, parallel prefix adder network is used to improve the speed and energy parameters. In addition to this the proposed structure called AND-OR-Invert (AOI) and OR-ANDInvert (OAI) gates are used for the skip logic and the Kogge-Stone adder is used. Kogge-stone adder is a type of parallel prefix. This design is used for digital circuits. In conventional digital circuits, a significant amount of energy is dissipated as the bits of information are lost during logical operations. Reversible logic is very important in low-power circuit design. This work proposes an optical reversible Carry-Skip Adder (CSKA) circuit. This design uses the Mach–Zehnder interferometers (MZI) due to its significant advantages such as high speed, low power, fast switching time and ease in fabrication. These CSKA designs use a minimum number of MZI switches. Finally, the comparison between these two circuits can be shown by using ModelSim software.