391 research outputs found
Quantum-dot Cellular Automata: Review Paper
Quantum-dot Cellular Automata (QCA) is one of the most important discoveries that will be the successful alternative for CMOS technology in the near future. An important feature of this technique, which has attracted the attention of many researchers, is that it is characterized by its low energy consumption, high speed and small size compared with CMOS. Inverter and majority gate are the basic building blocks for QCA circuits where it can design the most logical circuit using these gates with help of QCA wire. Due to the lack of availability of review papers, this paper will be a destination for many people who are interested in the QCA field and to know how it works and why it had taken lots of attention recentl
Error-power tradeoffs in QCA design
In this work we present an error-power tradeoff study in a Quantum-dot Cellular Automata (QCA) circuit design. Device parameter variation to optimize performance is a very crucial step in the development of a technology. In this work we vary the maximum kink energy of a QCA circuit to perform an error-power tradeoff study in QCA design. We make use of graphical probabilistic models to estimate polarization errors and non-adiabatic energy dissipated in a clocked QCA circuit and demonstrate the tradeoff studies on the basic QCA circuits such as majority gate and inverter. We also show how this study can be used by comparing two single bit adder designs. The study will be of great use to designers and fabrication scientists to choose the most optimum size and spacing of QCA cells to fabricate QCA logic designs
Teaching Nanotechnology by Introducing Crossbar-Based Architecture and Quantum-Dot Cellular Automata
The end of photolithography as the driver for Moore\u27s law is predicted within seven to twelve years and six different emerging technologies (mostly nanoscale) are expected to replace the current CMOS-based system integration paradigm. As nanotechnology is emerging, (1) there is a strong need for well-educated nanoscale systems engineers by industry, and (2) research and education efforts are also called to overcome numerous nanoscale systems issues. This paper is to propose a way to teach nanotechnology by introducing two emerging technologies: crossbar-based nanoarchitecture and quantum-dot cellular automata
Presentation of a fault tolerance algorithm for design of quantum-dot cellular automata circuits
A novel algorithm for working out the Kink energy of quantum-dot cellular automata (QCA) circuits and their fault tolerability is introduced. In this algorithm at first with determining the input values on a specified design, the calculation between cells makes use of Kink physical relations will be managed. Therefore, the polarization of any cell and consequently output cell will be set. Then by determining missed cell(s) on the discussed circuit, the polarization of output cell will be obtained and by comparing it with safe state or software simulation, its fault tolerability will be proved. The proposed algorithm was implemented on a novel and advance fault tolerance full adder whose performance has been demonstrated. This algorithm could be implemented on any QCA circuit. Noticeably higher speed of the algorithm than simulation and traditional manual methods, expandability of this algorithm for variable circuits, beyond of four-dot square of QCA circuits, and the investigation of several damaged cells instead just one and special cell are the advantages of algorithmic action
QCA-Based Majority Gate Design under Radius of Effect-Induced Faults
This paper presents reliable QCA cell structures for designing single clock-controlled majority gates with a tolerance to radius of effect-induced faults, for use as a basic building component for carry look-ahead adder. Realizable quantum computing is still well in the future due to the complexity of the quantum mechanics that govern them. In this regard, QCA-based system design is a challenging task since each cell\u27\u27s state must interact with all the cells that are in its energy-effective range in its clocking zone, referred to as its radius of effect. This paper proposes a design approach for majority gates to overcome the constraints imposed by the radius of effect of each cell with respect to clock controls. Radius of effect induces faults that lead to constraints on the clocking scheme of majority gates. We show majority gate structures that operate with multiple radius of effect-induced faults under a single clock control. The proposed design approach to a single clock controlled majority gate ultimately facilitate more efficient and flexible clocking schemes for complex QCA designs
Novel Defect Terminolgy Beside Evaluation And Design Fault Tolerant Logic Gates In Quantum-Dot Cellular Automata
Quantum dot Cellular Automata (QCA) is one of the important nano-level technologies for implementation of both combinational and sequential systems. QCA have the potential to achieve low power dissipation and operate high speed at THZ frequencies. However large probability of occurrence fabrication defects in QCA, is a fundamental challenge to use this emerging technology. Because of these various defects, it is necessary to obtain exhaustive recognition about these defects. In this paper a complete survey of different QCA faults are presented first. Then some techniques to improve fault tolerance in QCA circuits explained. The effects of missing cell as an important fault on XOR gate that is one of important basic building block in QCA technology is then discussed by exhaustive simulations. Improvement technique is then applied to these XOR structures and then structures are resimulated to measure their fault tolerance improvement due to using these fault tolerance technique. The result show that different QCA XOR gates have different sensitivity against this fault. After using improvement technique, the tolerance of XOR gates have been increased, furthermore in terms of sensitivity against this defect XORs show similar behavior that indicate the effectiveness of improvement have been made
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