DESIGN OF NOVEL MULTIPLEXER CIRCUITS IN QCA NANOCOMPUTING

Quantum-dot Cellular Automata (QCA) technology is a promising alternative nano-scale technology for CMOS technology. In digital circuits, a multiplexer is one of the most important components. In this study, an efficient and single layer 2 to 1 QCA multiplexer circuit is proposed using majority gate and inverter gate. In addition, efficient 4 to 1 and 8 to 1 QCA multiplexer circuits are implemented using this 2 to 1 multiplexer circuit. The developed multiplexer circuits are implemented in QCADesigner tool. According to the results, the developed 2 to 1, 4 to 1, and 8 to 1 multiplexer circuits utilize 16 (0.01μm2), 96 (0.11μm2), and 286 (0.43μm2) QCA cell (area). The results demonstrate that the proposed 8 to 1 multiplexer circuit reduces the cost by about 25%-99% compared to the existing multiplexer circuits

Novel Memory Structures in QCA Nano Technology

Quantum-dot Cellular Automata (QCA) is a new emerging technology for designing electronic circuits in nanoscale. QCA technology comes to overcome the CMOS limitation and to be a good alternative as it can work in ultra-high-speed. QCA brought researchers attention due to many features such as low power consumption, small feature size in addition to high frequency. Designing circuits in QCA technology with minimum costs such as cells count and the area is very important. This paper presents novel structures of D-latch and D-Flip Flop with the lower area and cell count. The proposed Flip-Flop has SET and RESET ability. The proposed latch and Flip-Flop have lower complexity compared with counterparts in terms of cell counts by 32% and 26% respectively. The proposed circuits are designed and simulated in QCADesigner software

An Ultra-Energy-Efficient Reversible Quantum-Dot Cellular Automata 8:1 Multiplexer Circuit

Energy efficiency considerations in terms of reduced power dissipation are a significant issue in the design of digital circuits for very large-scale integration (VLSI) systems. Quantum-dot cellular automata (QCA) is an emerging ultralow power dissipation approach, distinct from traditional, complementary metal-oxide semiconductor (CMOS) technology, for building digital computing circuits. Developing fully reversible QCA circuits has the potential to significantly reduce energy dissipation. Multiplexers are fundamental elements in the construction of useful digital circuits. In this paper, a novel, multilayer, fully reversible QCA 8:1 multiplexer circuit with ultralow energy dissipation is introduced. The power dissipation of the proposed multiplexer is simulated using the QCADesigner-E version 2.2 tool, describing the microscopic physical mechanisms underlying the QCA operation. The results show that the proposed reversible QCA 8:1 multiplexer consumes 89% less energy than the most energy-efficient 8:1 multiplexer circuit previously presented in the literature

Design of Power-Efficient Structures of the CAM Cell using a New Approach in QCA Nanoelectronics Technology

Quantum-dot Cellular Automata (QCA) is a new emerging nano-electronic technology. Owing to its many fa-vorable features such as low energy requirements, high speed, and small size, QCA is being actively suggested as a future CMOS replacement by researchers. Many digital circuits have been introduced in QCA technology, most of them aiming to reach the function with optimum construction in terms of area, cell count and power consumption. The memory circuit is the main building block in the digital system therefore the researchers paid attention to design the memory cells with minimum requirements. In this paper, a new methodology is intro-duced to design two forms of CAM cell. The proposed designs required two 2:1 multiplexers, one OR gate and one inverter. The first proposed design reduces the power consumption by 53.3%, 35% and 25.9% at (0.5 Ek, 1 Ek, and 1.5 Ek) while the second design by 53.2%, 31.9% and 20.5% (0.5 Ek, 1 Ek, and 1.5 Ek) respectively

Flip Flops Design in Quantum Dot Cellular Automata Technology: Towards Digitization

Quantum-Dot Cellular Automata (QCA) is a transistor-less technology. In QCA, Columbic repulsion between electrons in the quantum dots makes data transfer possible. This paper presents the design of flip flops using a proposed Rotated-Normal Cells with Displacement (RND) inverter and a cell interaction method. The SR latch, SR Flip Flop (FF), D FF, and T FF are developed using QCA. The proposed D FF gives total and average energy dissipation of 1.31e-002eV and 1.19e-003eV respectively. It also gives a delay of 1 clock phase.  The Proposed T FF provides total and average energy dissipation of 2.40e-002eV and 2.18e-003eV respectively, depicting efficient D FF and T FF in energy dissipation. The proposed SR Flip flop design gives an efficient area. The FFs with the proposed RND inverter and cell interaction method can be the best choice for future Nano communication to construct Nano circuits with less energy dissipation and high speed

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

A thermally aware performance analysis of quantum cellular automata logic gates

The high-performance digital circuits can be constructed at high operating frequency, reduced power dissipation, portability, and large density. Using conventional complementary-metal-oxide-semiconductor (CMOS) design process, it is quite difficult to achieve ultra-high-speed circuits due to scaling problems. Recently quantum dot cellular automata (QCA) are prosed to develop logic circuits at atomic level. In this paper, we analyzed the performance of QCA circuits under different temperature effects and observed that polarization of the cells is highly sensitive to temperature. In case of the 3-input majority gate the cell polarization drops to 50% with an increase in the temperature of 18 K and for 5 input majority gate the cell polarization drops more quickly than the 3-input majority. Further, the performance of majority gates also compared in terms of area and power dissipation. It has been noticed that the proposed logic gates can also be used for developing simple and complex and memory circuits

NOVEL SINGLE LAYER FAULT TOLERANCE RCA CONSTRUCTION FOR QCA TECHNOLOGY

Quantum-dot Cellular Automata (QCA) technology has become a promising and accessible candidate that can be used for digital circuits implementation at Nanoscale, but the circuit design in the QCA technology has been limited due to fabrication high-defect rate. So, this issue is an interesting research topic in the QCA circuits design. In this study, a novel 3-input Fault Tolerance (FT) Majority Gate (MG) is developed. Accordingly, an efficient 1-bit QCA full adder is developed using the developed 3-input MG. Then, a new 4-bit FT QCA Ripple Carry Adder (RCA) is developed based on the proposed 1-bit FT QCA FA. The developed circuits are implemented in the QCADesigner tool version 2.0.3. The results indicate that the developed QCA circuits provide advantages compared to other QCA circuits in terms of double and single cell missing defect, area and delay time

Designing memory cells with a novel approaches based on a new multiplexer in QCA Technology

Transistor-based CMOS technology has many drawbacks such that it cannot continue to follow the scaling of Moore’s law in the near future. These drawbacks lead researchers to think about alternatives. Quantum-dot Cellular Automata (QCA) is a nanotechnology that has unique features in terms of size and power consumption. QCA has the ability to represent binary numbers by electrons configuration. The memory circuit is a very important part of the digital system. In QCA technology, there are many approaches presented to accomplish memory cells in both RAM and CAM types. CAM is a type of memory used in high-speed applications. In this thesis, novel approaches to design memory cells are proposed. The proposed approaches are based on a 2:1 multiplexer. Using the proposed approach of RAM cell, a singular form of RAM cell (SFRAMC) is accomplished. In QCA technology, researchers strive to design electronic circuits with an emphasis on minimizing important metrics such as cell count, area, delay, cost and power consumption. The SFRAMC demonstrated significant improvements, with a reduction cell count, occupied area and power consumption by 25%, 24% and 36%. In terms of implementation cost, the SFRAMC saves 43% of the cost when compared to the previous best design. On the other hand, by using the proposed approach of CAM cell, two different structures of the QCA-CAM cell have been introduced. The first proposed CAM cell (FPCAMC) gives improvements in terms of cell count, and delay by 15% and 17% respectively. The second proposed CAM cell (SPCAMC) gives improvements in terms of cell count, and delay by 6% and 17% respectively. In terms of total power consumption, both FPCAMC and SPCAMC have an improvement of about 53% over the best-reported design. The above features of the proposed memory cells (RAM and CAM) could pave the road for designing energy-efficient and cost-efficient memory circuits in the future