Quantum dot Cellular Automata (QCA) is one of the promising technologies for nano scale implementation. The operation of QCA systems is based on a new paradigm generally referred to as processing-by-wire (PBW). This paper analyzes the defect tolerance properties of PBW when tiles are employed using molecular QCA cells. Based on a 3×3 QCA block, with different input/output arrangements, different tiles are analyzed and simulated using a coherence vector engine. The functional characterization and polarization level of these tiles for undeposited cell defects are reported. It is shown that novel features of PBW are possible due to spatial redundancy and QCA tiles are robust and inherently defect tolerant.

The design of circuits and systems in Quantum-dot Cellular Automata (QCA) is still in infancy. The basic logic primitive in QCA is the majority voter (MV), that is not a universal function; so, inverters (INV) are also required. Blocks (referred to as tiles) are utilized in this article. A tile with a combined logic function of MV and INV (MV-like function) is proposed. It is shown that the MV-like tile can be effectively used in logic design as basic primitive. Tiles based on both the fully populated (FP) and non-fully populated (NFP) grids are investigated in detail. Various arrangements in inputs and outputs are also possible among the 4 sides of a grid, thus defining different tiles. Using a coherence vector simulation engine, it is shown that the 3 × 3 grid offers versatile logic operation. Different combinational functions such as majority-like and wire crossing are obtained using these tiles. Tile-based design of different circuits is compared to gate-based and SQUARES designs.

Quantum-dot cellular automata (QCA) offers a new computing paradigm for nanotechnology. The basic logic elements of this technology are the majority voter (MV) and the inverter (INV). However, an experimental evaluation has shown that MV is not efficiently used during technology mapping by existing logic-synthesis tools. In this paper, we propose the design and characterization of a novel complex, yet very small, QCA logic gate: the and-or-inverter (AOI) gate. The paper presents a detailed simulation-based analysis of the AOI gate, as well as the study of QCA defects and their effects at the logic level. The AOI implements a universal logic gate; all elementary gates can be implemented by the AOI gate. Moreover, many two-level logic functions can be directly implemented by a single AOI gate. The AOI gate performs quite favorably, in terms of digital logic synthesis. Unlike MV, this gate is efficiently used by existing logic-synthesis tools. Our experimental data on synthesis of complex designs show that using the AOI gate instead of MV, results in up to 23.9% logic area savings, while improving the overall delay.

Quantum-dot Cellular Automata (QCA) offers a new computing paradigm in nanotechnology. The basic logic elements of this technology are the inverter and the majority voter. In this paper, we propose a novel complex and universal QCA gate: the And-Or-Inverter (AOI) gate, which is a 5 input gate consisting of 7 cells. This paper presents a detailed simulation-based analysis of the AOI gate as well as the characterization of QCA defects and study of their effects at logic level. Design implementations using the AOI gate are compared with the conventional CMOS and the majority voter-based QCA methodology. Testing of the AOI gate at logic level is also addressed, unique testing features of designs based on this complex gate have been investigated.

Summary form only given. There has been considerable research on quantum cellular automata (QCA) as a new computing scheme in the nanoscale regimes. A detailed simulation-based characterization of defects in different QCA logic and interconnect devices and study of their effects at logic-level are presented. Various failure mechanisms which can potentially happen during nanomannfacturing of these devices have been considered and simulated. Different implementations of QCA logic devices and interconnects are also compared in term of defect tolerance and testability. The same study is performed for new proposed QCA devices too. The simulation results show that additional fault models at logic level must be considered for testing of QCA-based circuits.

There has been considerable research on quantum dot cellular automata (QCA) as a new computing scheme in the nano-scale regimes. The basic logic element of this technology is majority voter. In this paper, a detailed simulation-based characterization of QCA defects and study of their effects at logic-level are presented. Testing of these devices is investigated and compared with conventional CMOS-based designs. Unique testing features of designs based on this technology are presented and interesting properties have been identified.