Today more than ever, we need high-speed circuits with low occupancy and low power as an alternative to CMOS circuits. Therefore, we proposed a new path to build nanoscale circuits such as Quantum-dot Cellular Automata (QCA). This technology is always prone to failure due to its very small size. Therefore, designers always try to design fault-tolerant gates and provide methods to increase the reliability of QCA. By adding redundant cells, the possibility of some defects such as cell omission and cell addition is somewhat reduced. However, in the face of defects such as stuck-at 0/1 faults, Clock fault and bridging fault. We can greatly increase the fault tolerance by appropriate placement and using fault tolerant gates with a suitable structure. In this paper, we design the XOR/XNOR gate with the approach of preventing stuck-at 0/1 fault, clock fault, and bridging fault using the first NNI gate tolerating cell addition fault. تفاصيل المقالة

Over the years, the design and implementation of fault-tolerant circuits have been one of the main concerns of the designers of electronic devices. Quantum Dot Cellular Automata (QCA) is a low-power, compact technology that is prone to various defects due to its small size. We can categorize these defects into three main groups: operational defects, manufacturing defects, and clocking defects. Using redundant cells, fault-tolerant gates, or changing the structure of the gates can improve the overall fault-tolerance of the circuit in some cases. However, increasing the fault-tolerance would lead to an increase in the occupied area and the delay of the gates. Therefore, designing a gate based on intercellular interactions with a minimum number of cells and maximum efficiency, which is also fault-tolerant, is a challenging task. In this paper, we present a new tile-shaped design for XOR and XNOR gates that is robust to the Missing cell, Extra cell, and Rotated cell defects by 25%, 55%, and 25%, respectively. That is why we call these gates TFXOR and TFXNOR, respectively. تفاصيل المقالة

Abstract
In this paper an optical filter based on 2D hexagonal photonic crystals that is suitable for the third window of optical communications is proposed. The structure consists of two waveguides including one L4 resonant cavity created by removing 4 holes between them, and one L1 resonant cavity by removing 1 hole near the output waveguide; moreover, 8 holes around the L4 cavity had been selected for optofluidic infiltration within them. This structure is very flexible, and different wavelengths in the third telecommunication window can be chosen using selective optofluidic infiltration with different refractive indices. Simplicity in design, no need to change the size of the holes and separating the desired wavelengths by selecting different optofluidic infiltration materials are the main features of this study. The plane-wave expansion method (PWE) and the finite-difference time-domain method (FDTD) have been used to extract the photonic bandgap and study the behavior of the photonic structure, respectively. تفاصيل المقالة