Methodology for Digital Circuit Designs in QCA Technology
Vijay Kumar Sharma, Prashant Kumar, Sudakar Singh ChauhanIntroduction:
Quantum-dot cellular automata (QCA) technology has emerged as a promising approach for developing low-power, high-density digital circuits in the ultra-nanoscale regime. QCA overcomes the short-channel limitations of complementary metal-oxide-semiconductor (CMOS) technology. These short-channel challenges become increasingly significant in ultrananoscale technology nodes, limiting the applicability of CMOS devices.
Methods:
In this work, a translated two-input XOR gate using only nine quantum-dot cells is proposed in QCA technology. The proposed XOR gate is employed to construct QCA-based half-adder and full-adder circuits. The designs leverage the concepts of half-distance and cell interaction, enabling efficient use of QCA cells. The proposed designs are verified using the QCA Designer tool and compared with previously published designs.
Results:
The proposed translated two-input XOR gate reduces cell count by 35.71% and delay by 50% compared to the best-reported design. It demonstrates 61.37% reliability against cell missing and addition defects. The developed half-adder reduces cell count by 41.18% and delay by 66.67%, while the full-adder reduces cell count by 21.74% compared to the best-reported designs.
Discussion:
The translated XOR gate employs half-distance translation to implement the logic function. Using this XOR gate, the half-adder and full-adder circuits are efficiently constructed in QCA technology. Key performance parameters are analyzed for comparison.
Conclusion:
The results indicate that the proposed translated XOR gate, along with the half-adder and full-adder designs, is effective and shows potential for future nanoscale computing applications.