Defect-tolerant logic implementation onto nanocrossbars by exploiting mapping and morphing simultaneously

Crossbar-based architectures are promising for the future nanoelectronic systems. However, due to the inherent unreliability, defect tolerance schemes are necessary to guarantee the successful implementations of any logic functions. Most of the existing approaches have been based on logic mapping, which exploits the freedom of choosing which variables/products (in a logic function) to map to which of the vertical/horizontal wires (in a crossbar). In this paper, we propose a new defect tolerance approach, namely logic morphing, by exploiting the various equivalent forms of a logic function. This approach explores a new dimension of freedom in achieving defect tolerance, and is compatible with the existing mapping-based approaches. We propose an integrated algorithmic framework, which employs both mapping and morphing simultaneously, and efficiently searches for a successful logic implementation in the combined solution space. Simulation results show that the proposed scheme boosts defect tolerance capability significantly with many-fold yield improvement, while having no extra runtime over the existing approach of performing mapping alone.