Modular Design of Ultra-Efficient Reversible Full Adder-Subtractor in QCA with Power Dissipation Analysis

Quantum-dot Cellular Automata (QCA) is an emerging nanotechnology and a possible alternative to overcome the limitations of complementary metal oxide semiconductor (CMOS) technology. One of the most attractive fields in QCA is the implementation of digital system. As, information loss is a major issue in irreversible digital computation systems. Therefore, reduced heat dissipation is an increasing demand for nano-scale computations. Reversible logic designs are good competitor towards sustainable digital systems. This paper presents two new reversible logic gates viz., 3 × 3-New Reversible Gate (3 × 3-NRG), and Modified Feynman Gate (MFG). The proposed gates are tested by designing an optimal reversible single layer full adder-subtractor circuit (RFAS). Based on the simulation results, it is observed that the proposed RFAS is an efficient arithmetic logic circuit and has reduced area, less circuit complexity and less number of clock delays over existing designs. In addition, a complete propagation path flow of the RFAS is also presented. Meanwhile, the energy dissipation analysis of the proposed RFAS is verified using three separate energy levels ( γ = 0.5 E k , γ = 1.0, E k and γ = 1.5 E k ), at T = 2 K in QCAPro tool. It is observed that the proposed RFAS design dissipates less energy compared to the traditional approaches.