Design and verification of down asynchronous counter using toggle flip-flop in QCA

Rohit Kumar Shaw – Angshuman Khan

   This study presents an innovative single-layered toggle flip-flop with highly polarized output designed specifically for Quantum-dot Cellular Automata (QCA), a cutting-edge nanocomputing approach. Building on the capabilities of this advanced flip-flop, a two-bit asynchronous down (ripple) counter was developed using QCADesigner 2.0.3, all within the QCA framework. The counter exhibits exceptional scalability and reliability, addressing key challenges in QCA circuit design. Energy efficiency and cost-effectiveness are standout features of the design, with a 53% improvement in energy efficiency and a 38% reduction in QCA-specific cost, as verified by QCADesigner-E 2.2 simulations. Furthermore, the physical stability of the proposed circuit was thoroughly examined through kink energy calculations, highlighting its robustness. These optimizations were achieved by avoiding complex crossovers and leveraging the benefits of the enhanced flip-flop architecture. The results underscore the significant potential of QCA in improving digital circuit performance, paving the way for more efficient, scalable, and cost-effective nanoelectronic designs and pushing the boundaries of next-generation nanocomputing solutions.

Keywords: asynchronous counter, QCA, T flip flop, ripple counter, kink energy

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