New robust QCA D flip flop and memory structures

Quantum dot Cellular Automata (QCA) is one of the candidate technologies to be replaced with CMOS. Using this technology, extra low power, extremely dense and very high speed structure is achieved. Since flip flops and memory cells are fundamental building blocks of digital circuits, constructing an efficient, dense, and simple QCA memory structure is of great importance. In this paper, using a robust 2:1 multiplexer, efficient level triggered and edge triggered QCA D flip flops and a memory cell with set/reset ability will be introduced. Simulation results demonstrate that the proposed desgins have efficient structures in terms of area, delay and complexity. Also, it is worth mentioning that these designs in contrast to the previous structures do not need any crossover wire. QCA designer, a common QCA layout design and a verification tool is employed to verify and simulate the proposed circuits.