A Five-input Majority Gate in Quantum-dot Cellular Automata

Quantum cellular automata (QCA) is expected to provide highly dense nanotechnology implementations of logic. However, unlike the CMOS technology, the designs in QCA are constrained by the limited number of basic gate structures. This paper describes an important new basic building block, a five input majority gate (MAJ5) in QCA technology. Many new functions can be directly implemented in a single MAJ5 gate. We demonstrate its use in a bit-serial adder. Since the designs using this gate generally use a smaller number of gates, wires and wire crossings, these designs are less susceptible to faults such as missing cells. This paper also presents a modified MAJ5 gate with a greater fault tolerance.