Design of Fault Tolerant Universal Logic in QCA

This work targets design of a robust universal logic gate in Quantum-dot cellular automata (RUQCA) that realizes majority and minority functions simultaneously with high fault tolerance. An alternative tile structure of QCA with hybrid cell orientations is formulated to maximize its throughput. The characterization of defective behaviour of RUQCA gate under cell deposition, cell misplacement and cell misalignment defects is investigated. The results show that the proposed RUQCA gate has very high fault coverage of 95%. The synthesis of fault tolerant multiplexer using RUQCA, with 90% fault tolerance, establishes the effectiveness of RUQCA.