Investigating multiple defects on a new fault-tolerant three-input QCA majority gate

Quantum-dot cellular automata (QCA) are a new technology used to fabricate digital circuits on the nanoscale in place of CMOS technology, which has limitations in device density. QCA devices are low in power consumption and high in speed due to their structure. Although some defects may occur during chemical fabrication, QCA gates and circuits can be designed to be fault-tolerant. The majority gate is most often used in QCA circuits; thus, many papers have investigated different structures for it and tried to design a fault-tolerant gate against only one defect. We have proposed a new structure for a three-input majority gate with a good percentage of truth output despite the multiple defects that may take place concurrently. A full adder is then designed using the proposed majority gate to demonstrate the degree of fault tolerance of QCA circuits made of fault-tolerant gates.