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

New efficient designs of reversible logic gates and circuits in the QCA technology

Quantum-dot cellular automata (QCA) is a developing nanotechnology, which seems to be a good candidate to replace the conventional complementary metal-oxide-semiconductor (CMOS) technology. The QCA has the advantages of very low power dissipation, faster switching speed, and extremely low circuit area, which can be used in designing nanoscale reversible circuits. In this paper, the new efficient QCA implementations of the basic reversible Gates such as: CNOT, Toffoli, Feynman, Double Feynman, Fredkin, Peres, MCL, and R Gates are presented based on the straight interactions between the QCA cells. Also, the designs of 4-Bit reversible parity checker and 3-bit reversible binary to Grey converter are introduced using these optimized reversible Gates. The proposed layouts are designed and simulated using QCADesigner software. In comparison with previous QCA designs, the proposed layouts are implemented with the minimum area, minimum number of cells, and minimum delay without any wire-crossing techniques. Also, in comparison with the CMOS technology, the proposed layouts are more efficient in terms of the area and power. Therefore, our designs can be used to realize quantum computation in ultralow power computer communication

Investigation of Molecular FCN for Beyond-CMOS: Technology, design, and modeling for nanocomputing

L'abstract è presente nell'allegato / the abstract is in the attachmen

Implementation of multi-CLB designs using quantum-dot cellular automata

CMOS scaling is currently facing a technological barrier. Novel technologies are being proposed to keep up with the need for computation power and speed. One of the proposed ideas is the quantum-dot cellular automata (QCA) technology. QCA uses quantum mechanical effects in the device at the molecular scale. QCA systems have the potential for low power, high density, and regularity. This thesis studies QCA devices and uses those devices to build a simple field programmable gate array (FPGA). The FPGA is a combination of multiple configure logical blocks (CLBs) tiled together. Most previous work on this area has focused on fixed logic and programmable interconnect. In contrast, the work at the Rochester Institute of Technology (RIT) has designed and simulated a configurable logic block (CLB) based on look-up tables (LUTs). This thesis presents a simple FPGA that consists of multiple copies of the CLB created by the RIT group. The FPGA is configured to emulate a ripple-carry adder and a bit-serial multiplier. The latency and throughput of both functions are analyzed. We employ a multilevel approach to design specification and simulation. QCADesigner software is used for layout and simulation of an individual CLB. For the FPGA, the high-level HDLQ Verilog library is used. This hybrid approach provides a high degree of confidence in reasonable simulation time

Feedbacks in QCA: a Quantitative Approach

In the post-CMOS scenario a primary role is played by the quantum-dot cellular automata (QCA) technology. Irrespective of the specific implementation principle (e.g., either molecular, or magnetic or semiconductive in the current scenario) the intrinsic deep-level pipelined behavior is the dominant issue. It has important consequences on circuit design and performance, especially in the presence of feedbacks in sequential circuits. Though partially already addressed in literature, these consequences still must be fully understood and solutions thoroughly approached to allow this technology any further advancement. This paper conducts an exhaustive analysis of the effects and the consequences derived by the presence of loops in QCA circuits. For each problem arisen, a solution is presented. The analysis is performed using as a test architecture, a complex systolic array circuit for biosequences analysis (Smith–Waterman algorithm), which represents one of the most promising application for QCA technology. The circuit is based on nanomagnetic logic as QCA implementation, is designed down to the layout level considering technological constraints and experimentally validated structures, counts up to approximately 2.3 milion nanomagnets, and is described and simulated with HDL language using as a testbench realistic protein alignment sequences. The results here presented constitute a fundamental advancement in the emerging technologies field since: 1) they are based on a quantitative approach relying on a realistic and complex circuit involving a large variety of QCA blocks; 2) they strictly are reckoned starting from current technological limits without relying on unrealistic assumptions; 3) they provide general rules to design complex sequential circuits with intrinsically pipelined technologies, like QCA; and 4) they prove with a real application benchmark how to maximize the circuits performance

Wave Pipelining for Majority-based Beyond-CMOS Technologies

The performance of some emerging nanotechnolo- gies benefits from wave pipelining. The design of such circuits re- quires new models and algorithms. Thus we show how Majority- Inverter Graphs (MIG) can be used for this purpose and we extend the related optimization algorithms. The resulting designs have increased throughput, something that has traditionally been a weak point for the majority of non-charge-based technologies. We benchmark the algorithm on MIG netlists with three different technologies, Spin Wave Devices (SWD), Quantum-dot Cellular Automata (QCA), and NanoMagnetic Logic (NML). We find that the wave pipelined version of the netlists have an improvement in throughput over power of 23×, 13×, and 5× for SWD, QCA, and NML, respectively. In terms of throughput over area ratio, the improvement is 5×, 8×, and 3×, respectively