Fast parallel-prefix Ling-carry adders in QCA nanotechnology

Ling-carry adders that use a Ladner-Fischer parallel-prefix algorithm for carry computation are explored for quantum-dot cellular automata (QCA) nanotechnology implementations. The results derived from drawn layouts, indicate that the proposed adders outperform in terms of delay all previously reported architectures explored for QCA implementations. The delay difference is becoming bigger in favor of the proposed adders as we move to larger wordlengths.