A New Clocking Scheme for Quantum-dot Cellular Automata Based Designs with Single or Regular Cells

Quantum-Dot Cellular Automata (QCA) is one of the newest technologies that play very important role to design Nano scale electronic devices that are likely to meet the requirements of the modern digital systems, as compared to micro fabricated devices in CMOS technology. In this paper, we proposed a new clocking scheme for QCA circuits, in which single phase cells (90°) or regular cells are used. We design combinational circuits with single phase cells. According to the previous clocking schemes there are no such schemes exist where only single phase cells are used for crossing as well as data propagation. In previous coplanar crossover schemes both cells (90° and 45°) are used for circuit design. The main limitation of these schemes is that there is a possibility of cross coupling between the two wires (one of 90° and another is 45°) during fabrication, when placement of any cells are misaligned. In the new scheme only single phase cells are used, so there is no misalignment of cells. Simulation results indicate that our designs with new clocking scheme achieve same results in comparison to the best previous relevant works. Simulation and verification are carried out by QCADesigner.