Designs of Level-Sensitive T Flip-Flops and Polar Encoders Based on Two XOR/XNOR Gates

Quantum-dot cellular automata is a novel nanotechnology that has the advantages of low energy dissipation, easy integration, and high computing speed. It is regarded as one of the powerful alternative technologies for the next generation of integrated circuits because of its unique implementation concept. In this paper, two XOR/XNOR gates are proposed. Level-sensitive T flip-flops, negative edge-trigger T flip-flops, two-to-one multiplexers, reversible gates, and (8, 4) polar encoders are implemented based on these two proposed logic gates. Simulation results show that, compared with the existing level-sensitive T flip-flops, the second proposed level-sensitive T flip-flop has fewer cells and lower energy dissipation; compared with the best (8, 4) polar encoder, the cell count and area of the second proposed (8, 4) polar encoder are decreased by 13.67% and 12.05%, respectively. The two XOR/XNOR gates have a stable output and low energy dissipation, which can be flexibly designed into complex quantum-dot cellular automata circuits.