A quantitative approach to testing in Quantum dot Cellular Automata: NanoMagnet Logic case

With the approaching of CMOS scaling limits the interest on emerging technologies is rapidly growing. Among emerging technologies, Quantum dot Cellular Automata (QCA) is one of the most studied. Particularly the magnetic implementation, NanoMagnet Logic (NML), offers very low power consumption and it combines logic and memory on a unique device. Despite the advantages of these technologies, QCA and NML working principle relies on the electric or magnetic interaction among neighbor cells, so it is very sensitive to process variations. The behavior of circuits is therefore largely affected by defects and fabrication variations. To effectively design circuits with these technologies, proper tools for testing circuits are necessary. In this work we present an innovative test environment for NML technology. The test algorithm is integrated in ToPoliNano, our design and simulation tool for emerging technologies, and it is specifically tailored to support the analysis of faults in large complexity circuits. Thanks to this tool it is possible to design and test complex NML circuits considering the effect of process variations in terms of Yield and Output Error Rate. The approach gives then feedback to the technologists, remarkably helping the future development of this technology. Moreover, notwithstanding the methodology is applied here to NML circuits only, it can also be successfully applied to QCA technology in general, greatly enhancing the value of the work we proposed here.