Design and Simulation of Reliable and Fast Nanomagnetic Conservative Quantum-dot Cellular Automata (NCQCA) Gate ​

Nanomagnetic Logic (NML) is a promising candidate for the real implementation of quantum-dot cellular automata (QCA) circuits and can be a proper alternative or complement to CMOS circuits. Like any other nanoscale technologies, NML circuits are also subject to fabrication variations. These variations along with fluctuations caused by thermal noise can affect the performance of these circuits. Therefore, design of NML circuits with high testability is an absolute necessity. Circuits based on conservative logic are inherently testable because of their specific properties. In this paper, considering the physical and geometrical properties of nanomagnets, a nanomagnetic conservative quantum-dot cellular automata (NCQCA) gate is designed and evaluated. This circuit can be used as the basic block for the realization of more complex conservative NML circuits. To implement this circuit, the design of the clocked nanomagnetic majority gate is also provided. The OOMMF physical simulation tool is used for simulation and evaluation. The results show the correct functionality of the proposed conservative gate at room temperature. It operates about 34% faster than the NML Fredkin gate. Moreover, the NML version of the conventional Fredkin gate takes 90% more area than the proposed design.

Low-Power Multiplexer Structures Targeting Efficient QCA Nanotechnology Circuit Designs

Quantum-dot cellular automata (QCA) technology is considered to be a possible alternative for circuit implementation in terms of energy efficiency, integration density and switching frequency. Multiplexer (MUX) can be considered to be a suitable candidate for designing QCA circuits. In this paper, two different structures of energy-efficient 2×1 MUX designs are proposed. These MUXes outperform the best existing design in terms of power consumption with approximate reductions of 26% and 35%. Moreover, similar or better performance factors such as area and latency are achieved compared to the available designs. These MUX structures can be used as fundamental energy-efficient building blocks for replacing the majority-based structures in QCA. The scalability property of the proposed MUXes is excellent and can be used for energy-efficient complex QCA circuit designs.

Implementing Logical Circuits with Four Phase Quantum Dot Cellular Clock using QCA Designer

Quantum Dot Cellular Automata (QCA) is treated as a most promising technology after CMOS techniques. The major advantages of QCA techniques are faster speed, lower energy consumption and smaller size. The implementation of clocks play very big role in the effective design of QCA circuits. In this paper, a QCA circuit is designed using the concept of QCA clocks. The proposed study describes a new method of implementing the logical function with power depletion analysis. The proposed logical function uses total number of 57 cells in which the area of each cell 372 nm2. The energy dissipation in this implementation is 18.79 meV and the total acquired area is 0.192 µm2. The proposed circuit is implemented utilizing QCA Designer. The proposal is excellent in the realization of nano-scale computing with minimal power utilization. The results are compared with the existing approaches and improvements of 6% in the area required and 7% in the number of cells are achieved