Novel Fault-Tolerant Processing in Memory Cell in Ternary Quantum-Dot Cellular Automata

Processing-in-memory (PIM) is a computational architecture in which the processing unit and memory are integrated into a single unit. Different technologies and methods can be used to implement PIM, but a more optimal design for PIM can be obtained by using quantum-dot cellular automata (QCA) and Akers structure. In the chemical manufacturing process of such circuits, the manufacturing defects and therefore malfunction are possible. One of the most common defects is cell omission, which has not yet been investigated in PIM based on binary or ternary QCA. One of the aims of this study is to improve fault tolerance (FT) by transforming the circuit structure from binary to ternary QCA. The results of evaluating different structures confirm achieving this aim. Moreover, in this study, new basic PIM cells are proposed, and then, AND, OR, and Exclusive-OR (XOR) gates are designed based on these cells in ternary quantum-dot cellular automata (TQCA). The ternary structure is used to improve circuit performance, storage density, and processing capability. For better analysis and comparison, binary structures are also implemented. The results of the evaluations show that the proposed ternary structures are efficient in terms of occupied area, latency, cost, FT, and complexity, as well as better efficiency in processing and storing data because of the three-valued structure.