A New Coplanar Full Adder/Subtractor in Quantum-Dot Cellular Automata Technology

The conventional CMOS technology faces different challenges such as fabrication in nanoscale which motivates researchers to find new alternatives to it for future high-performance systems. The quantum-dot cellular automata (QCA) is one of efficient nano-electronics technologies which can provide simple and efficient implementation of digital circuits in nanoscale. Due to the importance of addition in digital processors and embedded systems, there many QCA designs of adders and subtractors during the previous years. However, recently the unified design of adder and subtractor circuits has been considered to achieve overall area and delay reduction for digital computational circuits. In this paper, we present new coplanar design of a unified adder/subtractor unit with the QCA technology. Besides, the proposed single-layer design approach has been used to design separate half adder, half subtractor, half adder and full adder circuits. The comparison of circuit’s parameters of the proposed designs than previous works show the significant improvement in term of area, delay and cell number.