Reversible QCA based Full-adder and Subtractor in Nanotechnology

Transistor size is continuously decreasing and reaching up to 7nm and below due to CMOS/FinFET technology. This technology is about to saturate in the next few years and requires to be replaced with nano-technology. Quantum Dot Cellular Automata (QCA) technology has all those technical features to replace CMOS technology. However, Reversible logic circuits in QCA have very promising features like very high device density, ultra-low power dissipation, and faster switching speeds at nano-scale. Among various digital circuits, Full-adder and Full subtractor are the major part of arithmetic and logic circuits in processors, and hence improving the performance of these circuits, improves the performance of the processor to the great extent. In this review work, Various reversible logic gates have been studied and Full adder and subtractor circuits have been implemented in QCA technology. Simulation has been performed on freely available QCADesigner tool version-2.0.3 and results are compared.