Efficient design and implementation of a robust coplanar crossover and multilayer hybrid full adder–subtractor using QCA technology

Quantum dot cellular automaton (QCA) is a novel emerging nanometer-scale-based circuit design using nanocomputing technology, which overcomes the limitations of complementary MOS technology in the precondition of the circuit design area, power, and latency/delay. This paper presents an efficient design of crossover single-layer (coplanar) and multilayer novel hybrid full adder–subtractor circuits by implementing majority gate minimization functional J-map technique. The proposed circuits have been found more efficient in terms of minimum number of QCA cells, low latency, required area in µm², and reduced quantum cost as compared to existing QCA adder–subtractor designs and also avoid the thermodynamics problems occurring due to long QCA wires with the applied synchronization clocking method. In this paper, we have introduced 14 nm × 14 nm and 16 nm × 16 nm cell size QCA circuits and compared with an existing and proposed novel 18 nm × 18 nm single-layer and multilayer designs. Both designs are implemented by the QCADesigner-E tool with bistable vector and coherent vector energy setup in the Euler method and the Runge–Kutta method.