Single layer adder/subtractor using QCA nanotechnology for nanocomputing operations

Abstract

Quantum-dot cellular automata (QCA) nanotechnology is a suitable replacement for the widely accepted complementary metal oxide semiconductor (CMOS) technology. CMOS technology faces the issues of high-leakage current and non-scalability in the ultra-deep submicron (ultra-DSM) regime. It motivates the researchers to explore new technologies for further advancement of the field. QCA nanotechnology is energy-efficient technology and it overcomes the issues of CMOS technology in ultra-DSM regime. In this paper, a novel 3-input XOR structure is presented using QCA nanotechnology. The full adder and the full subtractor circuits based on the 3-input XOR gate are developed. A circuit for the full adder/subtractor nanostructure is proposed in the paper. All the proposed designs are optimal, fault-tolerant and single-layered. The proposed full adder contains only 21 QCA cells, while 22 QCA cells are required for the proposed full subtractor. The proposed full adder/subtractor structure consists of only 30 QCA cells. The proposed designs are compared with the existing designs for the number of QCA cells, total cell area, total covered area, area utilization, clock latency, QCA layout cost, and crossover requirement. The energy-efficient behaviour of the proposed circuits is calculated using the QCA Designer-E and the QCA Pro tools.