A novel controllable inverter and adder/subtractor in quantum-dot cellular automata using cell interaction based XOR gate

A promising nanotechnology, quantum-dot cellular automata (QCA), offers a new method for implementing digital systems at a nano-scale with significant improvements. In this paper, a novel three-input XOR gate that is based on a cell-interaction design is proposed. It can be used as a multifunctional gate by fixing one of the structure's inputs, which allows two-input XOR or XNOR gates to be easily implemented. By utilizing the three-input XOR gate, a coplanar compact full adder is created. Additionally, this paper focuses on an 8-bit adder/subtractor design using QCA. Novel design for an 8-bit adder and 8-bit controllable inverter are also proposed. The functionality and performance of the designs are demonstrated using the QCADesigner tool and by comparison with other existing designs. Moreover, a comprehensive power dissipation analysis is also conducted by QCAPro simulator.