Design of fault tolerant nano circuits in QCA using explicit cell interaction

Quantum-dot cellular automata (QCA) is the most prominent alternative to current CMOS VLSI technology. Till date, various combinational and sequential circuits are designed in QCA following the conventional digital logic principles. In this paper, an explicit QCA cell interaction principle is used for designing QCA circuits opposing the conventional digital gate-level implementation approach. Using the explicit QCA cell interaction, a two input XOR and two input XNOR gate is proposed. Simulation results show that the proposed XOR and XNOR gates are more fault tolerant than the existing gates found in the literature. To test the design capability of the proposed combinational gates, a one-bit comparator is designed which shows significant improvement in terms of area and gate count. The functionality of the proposed designs is verified with the help of QCADesigner simulator.