Quantum-dot Cellular Automata (QCA) has become one of the worthy studies for Nano-scale computing because we can achieve to low power consumption and high operating frequency by the design of reversible structures based on QCA technology. For this reason, this paper presents a novel fault-tolerance reversible ALU (Arithmetic Logic Unit) in QCA. Firstly, we have designed a new 3×3 RUG (Reversible Universal Gate), this gate achieves the lowest cost and overall cost between the best previous designs a reduction of 48.60% and 54.74%, respectively. Also, the proposed reversible ALU has analyzed with two main part RLU (Reversible Logic Unit) and RAU (Reversible Arithmetic Unit), the simulation results demonstrate that the proposed QCA designs are optimal in terms of circuit complexity and number of MVs (Majority Voters) in comparison with the other architectures, in our design coplanar crossover design approach is used. All proposed architectures are simulated using QCA Designer tool version 2.0.3.
