一种蔡氏硬件电路系统的研究

由于混沌是貌似随机的非随机运动。它对初始条件的极端敏感性。蔡氏电路出现后,通过非线性电路研究混沌产生涡卷成为可能,而蔡氏混沌电路产生涡卷吸引子方法多种多样,利用非线性多项式产生三涡卷混沌吸引子为例,对蔡氏电路进行数学模型分析,然后进行MATLAB仿真。再此基础上,对蔡氏电路进行Multisim仿真同样可以产生三涡卷混沌吸引子,并通过硬件电路系统实现,该硬件电路能够产生三涡卷吸引子,并且可作为一个信号发生电路应用。     

电流激励蔡氏电路混沌的解析预测

考虑到蔡氏电路受周围电路的影响,故将受周围影响的蔡氏电路做了等效处理,并将其等效为电流激励蔡氏电路。这里首次用解析的方法对三阶非线性微分方程能够产生混沌的参数范围进行预测,利用该方法得出电流激励蔡氏电路产生混沌的必要参数条件。通过数值仿真证明了该等效电路具有极其丰富的混沌动力学行为,仿真结果与解析预测结果有较好的吻合性。     

基于混沌同步的混沌脉冲定位调制研究

随着混沌理论和混沌同步的发展及完善，根据混沌脉冲定位调制（CPPM）的基本原理，提出一种基于混沌同步的混沌脉冲定位调制（CS—CPPM）实现方法，建立以蔡氏混沌同步电路和Logstic映射为例的实现模型，用EWB仿真软件对蔡氏二极管、蔡氏电路以及蔡氏同步电路进行分析和实现，最后用Matlab对整个系统进行仿真，实验结果论证了该方法的可行性．这样使得混沌脉冲定位调制信号可以利用现有的混沌映射实现．从而具有多样性和稳定的混沌特性。也使得混沌脉冲定位调制（CPPM）技术具有更多的实现途径和更深的研究与应用价值。     

基于MutiSIM的蔡氏混沌序列仿真研究

混沌序列是非线性方程描述的确定系统所产生的介于周期振荡与噪声之间的一种复杂振荡序列.蔡氏电路是一个经典,且简单的三阶自治系统,能够产生丰富的混沌现象。在对蔡氏电路进行数学建模的基础上,采用MultiSIM仿真软件对其进行仿真,并分析其产生的混沌信号的功率谱,从而找出一个最佳的电路参数,得到一个最好的,可用的混沌序列。     

基于CCCII非线性电阻实现的蔡氏电路及其研究

利用具有低电压、低功耗、低噪声以及电可调等优点的第二代电流控制电流传输器(CCCII),实现了一种具有"蔡氏二极管"特性的非线性电阻,并结合Pspice软件对由它构成的蔡氏电路进行了计算机仿真研究.仿真结果表明:调节非线性电阻电路的相关参数,不仅可以实现具有不同斜率的非线性电阻,而且由其构成的蔡氏电路也出现了诸如平衡态、周期、倍周期、单涡卷混沌吸引子、双涡卷混沌吸引子等丰富的混沌现象.同时还给出了蔡氏电路处于混沌状态时,各相关元件的参数变化范围.     

蔡氏混沌电路的单向耦合同步研究

基于Lyapunov稳定性理论,利用单向耦合方法,研究蔡氏电路混沌同步问题,指出蔡氏电路相互耦合同步存在的缺陷,通过仿真验证本文的结果.     

蔡氏混沌非线性电路及其频率特性研究

混沌电路是一种非线性电路，具有宽频谱特性，但在实际通信应用中，通信信道的带宽有一定限制，如何调节混沌电路的频谱范围成为混沌电路实际应用的一个问题。本文以蔡氏混沌电路为例，利用MATLAB软件分析蔡氏混沌电路产生的混沌信号及其频率特性。通过对蔡氏混沌电路中元器件R、L和C参数的调整，可以获得具有期望频谱范围的混沌信号。     

一种新型双忆阻混沌系统动力学及其电路实现研究

在经典的蔡氏混沌电路基础上,引入三次非线性磁控忆阻模型,利用一个磁控忆阻模型和一个荷控忆阻模型,外加一个负电导替换变形蔡氏电路中的蔡氏二极管,设计了一个五阶混沌电路,用常规的方法研究系统的基本动力学特性。通过数值仿真结果表明电路在参数变化情况下能产生Hopf分岔和反倍周期分岔两种分岔行为,并能产生双涡卷、单涡卷、极限环、同宿轨等不同轨道,出现了双单摆运动。观察混沌吸引子推广到功率与能量信号,观察到蝴蝶翅膀重叠的奇异吸引子。通过改变初始值,能产生共存吸引子和周期极限环共存现象。为了验证电路的混沌行为,将对设计的电路进行了PSpice仿真,电路仿真结果验证了理论分析的正确性。     

蔡氏电路混沌同步保密通讯

两个相同的蔡氏电路(Chua’s Circuit)互相耦合可以实现混沌(Chaos)同步是混沌研究的一个重要成果．也是探索蔡氏电路开发应用的基础。应用蔡氏电路的同步特性实现保密通讯是当前蔡氏电路开发应用研究的一个主要方向。本文在介绍蔡氏电路混沌同步特性的基础上，讨论主—从式蔡氏电路同步保密通讯系统及实现双向通讯和无线传输的可行性．并对这种保密通讯系统的安全性与鲁棒性(Robustness)作了简要的分析.     

蔡氏混沌电路的MATLAB仿真

对一种典型的混沌系统——蔡氏电路及优秀的数据处理与仿真工具MATLAB进行了简要介绍．应用MATLAB软件对蔡氏电路进行了仿真分析，并对仿真结果作了讨论，指出了这种研究方法的应用前景。     

基于二极管的限幅蔡氏电路实验研究

根据经典蔡氏电路的数学模型,获得系统各个变量之间的运算关系,利用运算放大器、电阻、电容及二极管等元器件,完成非线性限幅函数的电路设计,实现无电感元件的等效蔡氏电路硬件实验图。结果表明,通过调试电路中电阻值,可以直接从示波器观测到蔡氏电路的三个运动变量,包括周期、单涡卷、双涡卷等运动行为的时序图和相位图。搭建的电路结构简单,学生实验时调试容易,并且由于电路中不含电感元件,实验过程中混沌吸引子的稳定性也明显得到了提高。     

Wien bridge based RC chaos generator

A new circuit, which is formed by coupling a Chua diode with a Wien bridge oscillator in parallel, is presented. This circuit contains only resistors, capacitors and operational amplifiers. By choosing element values appropriately, this circuit is shown experimentally to exhibit various forms of chaotic behaviour     

On Current Feedback Operational Amplifier-Based Realization of Chua's Circuit

Because they offer some significant advantages over conventional operational amplifiers, current feedback operational amplifiers (CFOAs) have been used instead of voltage operational amplifiers (VOAs) in new implementations of the chaotic Chua’s circuit. In this study, after giving a comparative investigation of CFOA-based realizations of Chua’s circuit, we will present an alternative CFOA-based realization of Chua’s circuit combining the CFOA-based circuit topologies proposed for nonlinear resistor and inductor elements in the literature. This realization offers an alternative solution for readers studying Chua’s circuit and high-frequency chaotic oscillations. The PSpice simulation experiments performed in both the time and frequency domains confirm that the proposed circuit can generate the original chaotic oscillations of Chua’s circuit and that it exhibits excellent performance at high frequencies.     

基于饱和非线性模块的多涡卷混沌电路

针对分立元件构造的多涡卷混沌电路存在电源电压高、耗能多、频谱范围窄、电路体积大的问题,采用跨导电容结构,设计了一种将非线性模块、跨导器、电压反相器集成于一体的多涡卷混沌电路。非线性模块呈现饱和特性,通过调节电流源和MOS管宽长比来改变其特性曲线的转折点、饱和值、斜率,方便地构造出分段线性函数电路。设计了网格多涡卷Jerk系统和单方向多涡卷Chua系统,采用非线性模块分别搭建了Jerk系统中的阶梯波函数电路和Chua系统中的三角波函数电路。Pspice仿真结果证明了搭建的非线性模块和混沌电路设计、电路功能的正确性。     

基于CCII的集成混沌振荡器设计

集成化混沌振荡器是混沌在实际应用中的一种重要趋势,特别是在大规模的混沌系统的电子实现方面。为了使混沌振荡器的集成度更高,并且具有较宽的频带,本文提出了一种新型的电流模式混沌振荡器。通过对自治混沌振荡器的电路模型分析,在文氏混沌电路基础上,采用CCII电路代替电压运算放大器、跨导运算放大器等传统运算放大器,实现了正弦波振荡电路,通过采用NMOS管将两个正弦振荡电路耦合最终实现电流模式混沌振荡器,通过对该电流模式混沌振荡器建模并进行仿真分析,描述了该振荡器的混沌行为,验证了该混沌电路的有效性和可行性。再通过仿真结果对比表明该混沌振荡器相比于传统的文氏混沌振荡器功耗更小、噪声抑制能力更强,由其产生的混沌信号在频带宽度、随机程度方面都有明显提高,更适合芯片集成。     

Implementation of Chua's circuit using simulated inductance

In this study we describe how to build an inductorless version of the classic Chua's circuit. A suitable inductor for Chua's circuit is often hard to procure. The required inductor for the circuit is designed using simple circuit elements such as resistors, capacitors and operational amplifiers. The complete circuit can be implemented by using off-the-shelf components, and it can readily be integrated on a single chip. This design of Chua's circuit allows the original dynamics to be slowed down to just a few hertz, enabling implementation of sophisticated control schemes without severe time restrictions. Another novel feature of the circuit is that losses associated with capacitors due to leakages can easily be compensated by providing negative resistance using the same setup. The chaotic behaviour of the circuit is verified by PSpice and Multisim simulation and also by experimental study on a circuit breadboard. The results give excellent agreement with each other and with the results of previous investigators.     

A new multi-scroll Chua’s circuit with composite hyperbolic tangent-cubic nonlinearity: Complex dynamics,Hardware implementation and Image encryption application

In this paper, a new method for generating multi-scroll chaotic attractors via constructing a compound hyperbolic tangent-cubic nonlinear function in canonical Chua’s circuit is presented. The basic dynamic characteristics of the system are analyzed, including equilibrium points, bifurcation diagrams, Lyapunov exponents, phase portraits, time-domain diagrams and attractive basins. What is surprising is that the proposed multi-scroll Chua’s circuit also exhibits rich dynamic behaviors like coexisting multiple attractors, transient period, intermittent chaos and offset boosting. In addition, we put forward the application of the system in chaotic image encryption, and analyzed some security performance evaluation indexes to show that the new Chua’s chaotic cipher system has high security and reliable encryption performance. Finally, the hardware design and experiments of the chaotic digital circuits and image encryption are carried out. Both numerical simulation and FPGA experimental results verify the feasibility and usability of the proposed new multi-scroll Chua’s system.     

Novel voltage-mode biquad without external passive elements

This paper introduces a voltage-mode biquad filter using only active devices such as operational amplifiers and operational transconductance amplifiers (OTAs). The circuit configuration is obtained from Soderstrand's active-R state variable filter as a prototype. The proposed circuit can realize five different biquad transfer functions, and the circuit characteristics can be electronically tuned by adjusting the transconductance gains of the OTAs. An example is given, together with simulated results by PSPICE. The circuit configuration is very suitable for implementation in both bipolar and CMOS technologies.