文氏桥振荡器的簇发现象分析及实验验证

本文采用一对二极管将无源LC滤波器非线性耦合到文氏桥振荡器的并联桥臂替换电阻,实现了一种新颖的文氏桥振荡器;建立了该电路的动力学模型,开展了动力学行为分析.结果表明:文氏桥振荡器在给定的参数域内具有快慢效应.进一步研究了混沌簇发和周期簇发现象.本文研制了实验电路,该实验电路结构简单、易物理实现,实验测量和数值仿真两者结果一致,证明了理论分析的有效性.     

晶体管在RC振荡器中的非线性作用

在讲述晶体管文氏桥振荡器时,往往对晶体管的非线性作用只作定性的分析。本文的目的在于对文氏桥振荡器作一些定量的分析,以便对晶体管在RC振荡器中的非线性作用理解得更清楚。图1表示一个晶体管文氏桥振荡器实施电路。这个电路产生一个角频率为ω_o的正弦波振荡波形,测得的各点波形如图2所示。     

双忆阻Shinriki振荡器的超级多稳态和反单调性分析

本文通过在Shinriki振荡器中引入一个有源荷控忆阻,并且利用一个含绝对值项的磁控忆阻代替原电路中的串并联二极管回路,提出了一种含双忆阻器的Shinriki振荡器.根据电路拓扑结构图建立了忆阻振荡器的数学模型,开展了振荡器随电路元件参数变化时的共存分岔、周期-混沌状态转移等动力学特性分析.结果表明,双忆阻Shinriki振荡器对忆阻的参数值和初始条件有极大的依赖性,随着忆阻参数值和初始条件在特定域内变化,振荡器将呈现出共存反单调现象、不完全对称行为、超级多稳态等非线性动力学行为.此外,基于FPGA开发板完成了双忆阻Shinriki振荡器的数字电路仿真,在示波器上捕捉实验波形,验证了动力学分析的正确性.     

忆阻高通滤波电路准周期与混沌环面簇发振荡及慢通道效应

该文提出了一种忆阻高通滤波电路,它是由有源高通RC滤波器与二极管桥级联LC振荡器的忆阻模拟器并联耦合组成的。该文建立了电路方程与系统模型。基于分岔图、相平面图、庞加莱映射等数值仿真,开展了以反馈增益为可调参数的分岔分析,揭示了忆阻高通滤波电路中存在的准周期、混沌环面、混沌和多周期等簇发振荡行为。进一步地,通过快慢分析法,导出了快子系统的Hopf分岔集,并进而阐述了忆阻高通滤波电路慢通道效应的形成机理。最后,基于Multisim电路仿真验证了数值仿真结果。     

基于文氏振荡器的忆阻混沌电路

该文采用文氏桥振荡器和磁通控制的分段线性忆阻器,设计了一种新的单一参数控制的混沌电路。通过调节控制参数,该系统在忆阻器的非线性作用下,通过倍周期分岔产生了混沌和超混沌现象。利用常规的动力学分析手段研究了电路参数变化时系统的动力学特性,例如平衡点稳定性分析,李雅普诺夫指数谱和分岔图。为了验证电路的正确性,该文采用集成运放和压控开关实现了一个分段线性磁控忆阻器的模拟等效电路,并将该系统应用于提出的混沌电路,Pspice仿真结果与理论分析完全吻合。     

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。     

基于忆阻元件的五阶混沌电路研究

采用一个有源磁控忆阻器替换四阶蔡氏振荡器中的蔡氏二极管,导出了一个基于忆阻元件的五阶混沌电路,建立了相应电路状态变量的微分方程组.理论分析表明该忆阻混沌电路具有一个平衡点集,其稳定性随忆阻器初始状态变化而变化.采用常规的动力学分析手段研究了忆阻器初始状态发生变化时电路的动力学特性.数值仿真结果验证了理论分析的正确性.     

基于滤波器和忆阻二极管桥的振荡器实验方案与验证

非线性普遍存在于实际电路中。本文基于Sallen-Key滤波器和忆阻二极管桥设计了一类忆阻振荡器电路。并以一个忆阻振荡器为例，制定了实验方案，完成了实验验证。结果表明，通过改变电路元件参数值，可观测到周期极限环、准周期振荡以及混沌振荡等非线性现象。该电路结构简单，调试方便，现象丰富。该实验方案可作为本科课程设计的重要研究性内容，加深学生对电路中非线性现象的理解。     

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。     

Colpitts振荡电路动力学特性的PSPICE仿真分析

以Colpitts振荡器电路为例,在建立Colpitts电路模型的基础上,对其进行PSpice仿真研究,观察状态变量分别在时域和频域中的变化.通过调整电路元件的参数,观察Colpitts电路中动力学行为的演变过程,得到了与理论分析相吻合的结果.可以发现,电路处于混沌态和准周期态的参数组合不是唯一的.     

三维多涡卷Colpitts混沌系统及其数字硬件实现

基于混沌吸引子形成的机理,利用单位锯齿波函数改造混沌Coipitts振荡器模型,提出了一个新三维多涡卷混沌系统,生成了(2K+1)涡卷混沌吸引子.单位锯齿波函数的引入,增加了系统的指数2平衡点,从而形成多涡卷吸引子.采用常规的动力学分析方法,研究了该多涡卷混沌系统的动力学特性,研究结果表明所提出的系统的Hopf分岔点仅...     

Modified Wien-bridge oscillator for chaos

A nonlinear Wien-bridge based circuit generating chaotic oscillations is reported. The generator contains a single opamp and a single nonlinear device displaying a current saturation characteristic. The oscillator is described by a set of three ordinary differential equations. Experimental results are included demonstrating the circuit performance     

基于考毕兹振荡器的宽带混沌电路设计

针对某些雷达、通信等系统在应用中对混沌信号频域带宽的要求,设计了一种基于考毕兹振荡器电路的宽带混沌信号发生器。该混沌信号产生电路由考毕兹振荡器为基本谐振电路、级联若干容阻串并联单元的选频网络构成,混沌信号的上下限频率分别由基本谐振电路和第一节容阻串并联网络参数决定,通带频谱的平坦性受其他级联选频网络影响。根据初步分析和仿真试验,该混沌电路组成结构简单,能够产生带宽超过60MHz较为平坦的宽带混沌信号。     

Wien-bridge chaotic circuit with comparator

A Wien-bridge-based circuit generating chaotic oscillations has been designed and investigated both numerically and experimentally. The oscillator contains an operational amplifier, a Wien-bridge used as a resonance loop, an additional RC inertial circuit, and a comparator employed as a nonlinear device. The waveforms and the Lyapunov exponents are presented. The synchronisation properties have been investigated     

Third-order RLCM-four-elements-based chaotic circuit and its coexisting bubbles

This paper presents a new third-order RLCM-four-elements-based chaotic circuit, in which the memristor element is equivalently implemented by a diode-bridge cascaded with an inductor. Mathematical model is established and its equilibrium stability is analyzed. The dynamical properties of the memristive chaotic circuit are disposed by MATLAB numerical simulations and confirmed by breadboard experimental measurements. In particular, the antimonotonicity phenomena of coexisting periodic and chaotic bubbles are observed under some specified control system parameters and the evolutions of coexisting bubbles are exhibited with the variations of two control system parameters. The presented memristive chaotic circuit is very simple and only third-order but can emerge complex dynamics with chaos, period, coexisting bifurcation modes, and coexisting bubbles.     

A novel current-controlled memristor-based chaotic circuit

In this paper, a novel third-order autonomous memristor-based chaotic circuit is proposed. The circuit has simple topology and contains only four elements including one linear negative impedance converter-based resistor, one linear capacitor, one linear inductor, and one nonlinear current-controlled memristor. Firstly, the voltage-current characteristic analysis of the memristor emulator for different driving amplitudes and frequencies are presented. With dimensionless system, the symmetry, equilibrium point and its stability are analysed. It is shown that the system has two unstable saddle-foci and one unstable saddle. A set of typical parameters are chosen for the generation of chaotic attractor. Differing from the common period-doubling bifurcation route in smooth dynamical systems, this memristive system shows abrupt transition from the coexisting period-1 limit cycles to robust chaos when varying system parameters. Various dynamical behaviors are analysed using the numerical simulations and circuit verifications.     

An AGC Circuit Design for a Variable-Frequency Sinusoidal Oscillator with Wide Frequency Range and Low Distortion Level

An up-down counter, multiplier, digital-to-analog (D/A) converter, and high-speed comparators are employed to achieve an automatic gain control (AGC) circuit, which corrects the pair of characteristic roots of the overall system automatically to the imaginary axis of the complex frequency plane. A negative feedback technique with digital hardware is applied on the loop gain control. No lowpass filter is needed to detect the oscillation amplitude. Thus, this technique is suitable for sinusoidal oscillators with a wide oscillation frequency range. Wien-bridge and phase-shift oscillators with an oscillation frequency range from 17 Hz to 1 MHz are tested with the proposed AGC circuit. The total harmonic distortions of the Wien-bridge sinusoidal oscillator with the proposed AGC circuit are verified to be very small. An application to a variable-frequency sinusoidal oscillator is also described. The experimental results demonstrate the static characteristics and dynamic responses of the overall system.     

Chaotic Oscillators Derived from Sinusoidal Oscillators Based on the Current Feedback Op Amp

A collection of novel chaotic oscillators displaying behavior similar to that of the chaotic Colpitts oscillator and requiring the same number and type of energy storage elements is proposed. The oscillators use as an active element the current feedback op amp (CFOA) mostly employed as a current negative impedance converter (INIC). Nonlinearity is introduced through a two-terminal voltage-controlled nonlinear device with an antisymmetric driving-point characteristic. The chaos generators are designed based on sinusoidal oscillators that have been modified for chaos in a semi-systematic manner. By using CFOAs, several attractive features are attained, in particular suitability for high frequency operation. Systems of third- and fourth-order ordinary differential equations describing the chaotic behaviors are derived. Experimental results, PSpice circuit simulations and numerical simulations of the derived mathematical models are included.