Huanqing Cui

Design and Simulation of Turbo Encoder in Quantum-Dot Cellular Automata

Quantum-dot cellular automata (QCA) is a potential nanoelectronic technology for information processing. To be considered as a suitable CMOS candidate, QCA must be able to implement complex real-time applications of bit-serial information processing, which lacks of enough investigation. Turbo encoding is one of such applications, which refers to three representative issues of bit-serial circuits: convolution computation, feedback, and serial data permutation. The inherent shift-register nature of QCA offers an advantage to performing convolution computation but poses handicaps to resolve the latter two issues. How to manage the ambivalent effects of shift-register nature is investigated in this paper, which determines the efficient design of Turbo encoder. A strobe scheme based on main-branch wire crossing is proposed to efficiently make data choosing that is the communally key procedure of the implementation of feedback and serial data permutation. On this basis, a method of implementing recursive convolutional encoder with multifeedback is proposed. A two-stage pipelining interleaver is presented. Finally, a Turbo encoder is implemented using QCA based on these approaches and simulation demonstrates that it performs well.

Voltage Tunability of Magnetic Vortex Gyrotropic Mode Frequency in an Elliptical Magnetostrictive Nanodisk

Micromagnetic simulations predict vortex gyrotropic frequency variations induced by voltage-generated uniaxial stress in a soft, elliptical, magnetostrictive nanodisk. The gyrotropic frequency decreases when the direction of uniaxial stress changes from the major axis of the nanodisk to the minor axis, whereas a more notable downshift of the gyrotropic frequency occurs when the magnitude of the stress increases. The mechanism is analyzed in terms of the stiffness coefficients, which are calculated based on the vortex dynamic energy profile. This voltage tunability of gyrotropic frequency paves the way for the realization of vortex oscillators and frequency-controlled vortex computer memory with ultralow power consumption.

Spin-orbit torque induced magnetic vortex polarity reversal utilizing spin-Hall effect

We propose an effective magnetic vortex polarity reversal scheme that makes use of spin-orbit torque introduced by spin-Hall effect in heavy-metal/ferromagnet multilayers structure, which can result in subnanosecond polarity reversal without endangering the structural stability. Micromagnetic simulations are performed to investigate the spin-Hall effect driven dynamics evolution of magnetic vortex. The mechanism of magnetic vortex polarity reversal is uncovered by a quantitative analysis of exchange energy density, magnetostatic energy density, and their total energy density. The simulation results indicate that the magnetic vortex polarity is reversed through the nucleation-annihilation process of topological vortex-antivortex pair. This scheme is an attractive option for ultra-fast magnetic vortex polarity reversal, which can be used as the guidelines for the choice of polarity reversal scheme in vortex-based random access memory.We propose an effective magnetic vortex polarity reversal scheme that makes use of spin-orbit torque introduced by spin-Hall effect in heavy-metal/ferromagnet multilayers structure, which can result in subnanosecond polarity reversal without endangering the structural stability. Micromagnetic simulations are performed to investigate the spin-Hall effect driven dynamics evolution of magnetic vortex. The mechanism of magnetic vortex polarity reversal is uncovered by a quantitative analysis of exchange energy density, magnetostatic energy density, and their total energy density. The simulation results indicate that the magnetic vortex polarity is reversed through the nucleation-annihilation process of topological vortex-antivortex pair. This scheme is an attractive option for ultra-fast magnetic vortex polarity reversal, which can be used as the guidelines for the choice of polarity reversal scheme in vortex-based random access memory.

Three-dimensional quantum cellular neural network and its application to image processing

A three-dimensional quantum cellular neural network is proposed by using the quantum cellular automata as neuron cells. The three-dimensional quantum cellular neural network consists of two layers of quantum cellular automata array and possesses the A cloning template, B cloning template, and threshold. The image processing functions such as hole filling and corner detecting were performed by using the polarization of quantum cellular automata as pixel value and selecting different cloning templates and thresholds. The SIMULINK model is employed to simulate image processing functions and the simulation results demonstrate the effectiveness of the proposed quantum cellular neural networks.

Accurate reliability analysis method for quantum-dot cellular automata circuits

Probabilistic transfer matrix (PTM) is a widely used model in the reliability research of circuits. However, PTM model cannot reflect the impact of input signals on reliability, so it does not completely conform to the mechanism of the novel field-coupled nanoelectronic device which is called quantum-dot cellular automata (QCA). It is difficult to get accurate results when PTM model is used to analyze the reliability of QCA circuits. To solve this problem, we present the fault tree models of QCA fundamental devices according to different input signals. After that, the binary decision diagram (BDD) is used to quantitatively investigate the reliability of two QCA XOR gates depending on the presented models. By employing the fault tree models, the impact of input signals on reliability can be identified clearly and the crucial components of a circuit can be found out precisely based on the importance values (IVs) of components. So this method is contributive to the construction of reliable QCA circuits.