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Boundary Dynamics of Memcapacitor in Voltage-Excited Circuits and Relaxation Oscillators

This paper discusses the boundary dynamics of the charge-controlled memcapacitor for Joglekar’s window function that describes the nonlinearities of the memcapacitor’s boundaries. A closed form solution for the memcapacitance is introduced for general doping factor (Formula presented.)p. The derived formulas are used to predict the behavior of the memcapacitor under different voltage excitation sources showing a great matching with the circuit simulations. The effect of the doping factor (Formula presented.) on the time domain response of the memcapacitor has been studied as compared to the

Circuit Theory and Applications

Nonlinear charge-voltage relationship in constant phase element

The constant phase element (CPE) or fractional-order capacitor is an electrical device that has an impedance of the form Z(s)=1/Cαsα, where Cα is the CPE parameter and α is a fractional dispersion coefficient of values between 0 and 1. Here we show that in the time-domain the classical linear charge-voltage relationship of ideal capacitors, q=C·v, is not valid for CPEs. In fact the relationship is nonlinear and can be expressed as q=C(v;Cα,α)·v. We verify our findings using (i) circuit simulations of an integer-order emulator of a CPE, and (ii) experimental results from a commercial

Circuit Theory and Applications

FPGA Implementation of Delayed Fractional-Order Financial Chaotic System

This paper proposes digital design and realization on Field-Programmable Gate Array (FPGA) of the Fractional-order (FO) delayed financial chaotic system. The system is solved numerically using the approximated Grünwald-Letnikov (GL) method. For the purpose of FPGA realization, the short memory principle and an approximate GL with limited window size are utilized. Lookup Tables (LUTs) are employed to store the required state values in order to compute the delayed terms. The proposed digital design is implemented on Artix-7 FPGA platform XC7A100T and realized experimentally on the oscilloscope

Circuit Theory and Applications

FPGA implementation of two fractional order chaotic systems

This paper discusses the FPGA implementation of the fractional-order derivative as well as two fractional-order chaotic systems where one of them has controllable multi-scroll attractors. The complete hardware architecture of the Grünwald-Letnikov (GL) differ-integral is realized with different memory window sizes. As an application of the proposed circuit, a complete fractional-order FPGA implementation of Liu chaotic system is introduced with different fractional-orders. Moreover, a fractional-order controllable heart and V-shape multi-scrolls chaotic systems are verified in the case of

Circuit Theory and Applications

Digital Emulation of a Versatile Memristor with Speech Encryption Application

Memristor characteristics such as nonlinear dynamics, state retention and accumulation are useful for many applications. FPGA implementation of memristor-based systems and algorithms provides fast development and verification platform. In this work, we first propose a versatile digital memristor emulator that exhibits either continuous or discrete behaviors, similar to valence change memories (VCM) and the electrochemical metallization memories. Secondly, the proposed memristor emulator is used to design a chaotic generator circuit utilizing the memristor's nonlinearity. Finally, the chaotic

Circuit Theory and Applications

Fractional controllable multi-scroll V-shape attractor with parameters effect

This paper is an extension of V-shape multi-scroll butterfly attractor in the fractional-order domain. The system complexity is increased by the new dynamics introduced by the fractional operator which make it more suitable for random signal generator. The effect of system parameters on controlling the attractor shape is investigated and compared with the integer order attractor. Maximum Lyapunov exponent is calculated for both integer and fractional orders attractors to prove the complexity of fractional chaotic system using time series. © 2017 IEEE.

Circuit Theory and Applications

Fractional inverse generalized chaos synchronization between different dimensional systems

In this chapter, new control schemes to achieve inverse generalized synchronization (IGS) between fractional order chaotic (hyperchaotic) systems with different dimensions are presented. Specifically, given a fractional master system with dimension n and a fractional slave system with dimension m, the proposed approach enables each master system state to be synchronized with a functional relationship of slave system states. The method, based on the fractional Lyapunov approach and stability property of integer-order linear differential systems, presents some useful features: (i) it enables

Circuit Theory and Applications

Fractional inverse generalized chaos synchronization between different dimensional systems

In this chapter, new control schemes to achieve inverse generalized synchronization (IGS) between fractional order chaotic (hyperchaotic) systems with different dimensions are presented. Specifically, given a fractional master system with dimension n and a fractional slave system with dimension m, the proposed approach enables each master system state to be synchronized with a functional relationship of slave system states. The method, based on the fractional Lyapunov approach and stability property of integer-order linear differential systems, presents some useful features: (i) it enables

Circuit Theory and Applications

FPGA implementation of fractional-order Chua's chaotic system

This paper introduces FPGA implementation of fractional order double scrolls chaotic system based on Chua circuit. Grunwald-Letnikov's (GL) definition is used to generalize the chaotic system equations into the fractional-order domain. Xilinx ISE 14.5 is used to simulate the proposed design and Artix-7 XC7A100T FPGA is used for system realization. Experimental results are presented on digital oscilloscope and the error between theoretical and experimental results is calculated. Also, various interesting attractors are obtained with respect to different parameters values and window sizes. Some

Circuit Theory and Applications

Two topologies of fractional-order oscillators based on CFOA and RC networks

This paper presents two general topologies of fractional order oscillators. They employ Current Feedback Op-Amp (CFOA) and RC networks. Two RC networks are investigated for each presented topology. The general oscillation frequency, condition and the phase difference between the oscillatory outputs are investigated in terms of the fractional order parameters. Numerical simulations and P-Spice simulation results are provided for some cases to validate the theoretical findings. The fractional order parameters increase the design flexibility and controllability which is proved by the provided

Circuit Theory and Applications