Design and analysis of efficient QCA reversible adders

Quantum-dot cellular automata (QCA) as an emerging nanotechnology are envisioned to overcome the scaling and the heat dissipation issues of the current CMOS technology. In a QCA structure, information destruction plays an essential role in the overall heat dissipation, and in turn in the power consumption of the system. Therefore, reversible logic, which significantly controls the information flow of the system, is deemed suitable to achieve ultra-low-power structures. In order to benefit from the opportunities QCA and reversible logic provide, in this paper, we first review and implement prior reversible full-adder art in QCA. We then propose a novel reversible design based on three- and five-input majority gates, and a robust one-layer crossover scheme. The new full-adder significantly advances previous designs in terms of the optimization metrics, namely cell count, area, and delay. The proposed efficient full-adder is then used to design reversible ripple-carry adders (RCAs) with different sizes (i.e., 4, 8, and 16 bits). It is demonstrated that the new RCAs lead to 33% less garbage outputs, which can be essential in terms of lowering power consumption. This along with the achieved improvements in area, complexity, and delay introduces an ultra-efficient reversible QCA adder that can be beneficial in developing future computer arithmetic circuits and architecture

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 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

Novel ultra-energy-efficient reversible designs of sequential logic quantum-dot cellular automata flip-flop circuits

The version of record of this article, first published in [The Journal of Supercomputing], is available online at Publisher’s website: http://dx.doi.org/10.1007/s11227-023-05134-1Quantum-dot cellular automata (QCA) is a technological approach to implement digital circuits with exceptionally high integration density, high switching frequency, and low energy dissipation. QCA circuits are a potential solution to the energy dissipation issues created by shrinking microprocessors with ultra-high integration densities. Current QCA circuit designs are irreversible, yet reversible circuits are known to increase energy efficiency. Thus, the development of reversible QCA circuits will further reduce energy dissipation. This paper presents novel reversible and irreversible sequential QCA set/reset (SR), data (D), Jack Kilby (JK), and toggle (T) flip-flop designs based on the majority gate that utilizes the universal, standard, and efficient (USE) clocking scheme, which allows the implementation of feedback paths and easy routing for sequential QCA-based circuits. The simulation results confirm that the proposed reversible QCA USE sequential flip-flop circuits exhibit energy dissipation less than the Landauer energy limit. Irreversible QCA USE flip-flop designs, although having higher energy dissipation, sometimes have floorplan areas and delay times less than those of reversible designs; therefore, they are also explored. The trade-offs between the energy dissipation versus the area cost and delay time for the reversible and irreversible QCA circuits are examined comprehensively

Design and performance analysis of a new efficient coplanar quantum-dot cellular automata adder

Quantum-dot cellular automata (QCA) nanotechnology has the potential for revolutionizing the way computers are used. QCA computing has numerous advantages of ultra-low energy dissipation, improved performance and high device density. An adder is the most elementary component in arithmetic units of processors. Lot of work has been in progress to design and implement efficient adder circuits in QCA nanotechnology. This paper presents design and performance analysis of a new efficient coplanar adder in QCA nanotechnology. The proposed adder design uses 20% less QCA cells as compared to previous similar design due to better arrangement of QCA cells in the layout and has a delay of 1 clock cycle with an area of 0.04 µm2. The proposed adder has 19% less average leakage energy dissipation, 28% less average switching energy dissipation, and 25% less average energy dissipation than the best reported previous coplanar adder design. The cost function of proposed efficient adder is equal to best reported previous coplanar adder

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

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