超宽带微波混沌电路及其负阻提升技术的研究

发布时间：2018-05-20 21:24

本文选题：超宽带 + 微波　；参考：《南京大学》2015年博士论文

【摘要】：混沌信号具有宽带、非线性、类噪声的功率谱等特性,可以广泛应用于保密通信、超宽带通信、扩频通信、混沌雷达、电子对抗等诸多领域。混沌电路研究的核心之一是混沌信号发生器的设计。信号带宽是混沌信号发生器的重要性能指标,影响混沌信号带宽的主要因素是混沌振荡基本频率,因此混沌信号发生器设计的主要目标是提升混沌振荡基本频率以获得超宽带的混沌信号带宽。Colpitts混沌电路可以工作在微波频段,逐渐成为混沌电路的研究热点。不过经典Colpitts混沌电路由于受到低品质因子Q值及晶体管基极-集电极寄生电容的影响,混沌振荡基本频率只能达到所使用晶体管截止频率的十分之一左右。本文通过解非线性状态方程得出经典混沌电路的混沌分岔图,并以混沌分岔图为基础,从数学和物理的角度解释混沌振荡与一般振荡之间的区别。利用导出的振荡器负阻表达式,定性和定量的分析寄生电容对负阻的影响。然后将振荡器中的负阻提升技术引入到混沌电路的设计中,并设计了双电感负阻提升的混沌电路、两级负阻提升的混沌电路和差分结构的混沌电路,实现混沌振荡频率、带宽和稳定性的提升。理论及仿真分析表明：1、优化的双电感结构混沌电路在满足混沌振荡的条件下能有效抑制基极-集电极寄生电容对负阻的影响；2、通过在单级混沌电路中加入一级负阻电路而形成的两级负阻提升结构的混沌电路可以实现负阻提升2倍；3、基于双电感和两级负阻提升技术提出的差分结构混沌电路,提升了混沌电路的稳定性。稳定性的提升进一步使得电路的调试更容易,因而可以利用器件的寄生电容作为主振荡器件,将混沌振荡频率推进到器件所能达到的极限频率。本文分别基于BFG520三极管和2um砷化镓HBT工艺对新型混沌电路进行了设计实现,测试最高混沌基本振荡频率达到了2.82GHz以上,较现有公开报道的最高基频1.60GHz提升了75%,具有连续混沌信号频谱的总带宽达到了9.04GHz(0.56GHz-9.60GHz),功率谱差值10dB以内的连续频谱带宽达到了：1.92GHz(1.28GHz-3.20GHz)、2.30GHz(3.20GHz-5.50GHz)、3.20GHz(6.40GHz-9.60GHz)。
[Abstract]:Chaotic signal has the characteristics of wideband, nonlinear and noise-like power spectrum. It can be widely used in many fields, such as secure communication, UWB communication, spread spectrum communication, chaotic radar, electronic countermeasure and so on. The design of chaotic signal generator is one of the core of chaotic circuit research. Signal bandwidth is an important performance index of chaotic signal generator. The main factor affecting the bandwidth of chaotic signal is the basic frequency of chaotic oscillation. Therefore, the main goal of chaotic signal generator design is to increase the basic frequency of chaotic oscillation to obtain ultra-wideband chaotic signal bandwidth. Colpitts chaotic circuit can work in microwave frequency band, and gradually become the research hotspot of chaotic circuit. However, due to the influence of low quality factor Q and parasitic capacitance of transistor base collector, the basic frequency of chaotic oscillation of Colpitts chaotic circuit can only reach about 1/10 of the cutoff frequency of the transistor used. In this paper, the chaotic bifurcation diagram of classical chaotic circuit is obtained by solving the nonlinear state equation. Based on the chaotic bifurcation diagram, the difference between chaotic oscillation and general oscillation is explained from the point of view of mathematics and physics. The influence of parasitic capacitance on negative resistance is analyzed qualitatively and quantitatively by using the derived expression of negative resistance of oscillator. Then, the negative resistance lifting technique of the oscillator is introduced into the design of chaotic circuit, and the chaotic circuit with double inductor negative resistance lifting, the chaotic circuit with two-stage negative resistance lifting and the chaotic circuit with differential structure are designed to realize the chaotic oscillation frequency. Improved bandwidth and stability. Theoretical and simulation analysis show that the optimized two-inductor chaotic circuit can effectively suppress the effect of parasitic capacitance of base collector on negative resistance under the condition of chaotic oscillation. The chaotic circuit with two-stage negative-resistance lifting structure formed by resistive circuit can realize 2-fold negative-resistance lifting. Based on the technique of double inductance and two-stage negative-resistance lifting, the chaotic circuit with differential structure is proposed. The stability of chaotic circuit is improved. The improvement of stability makes it easier to debug the circuit, so the parasitic capacitance of the device can be used as the main oscillator to push the chaotic oscillation frequency to the limit frequency that the device can achieve. In this paper, a novel chaotic circuit is designed and implemented based on BFG520 transistor and 2um GaAs HBT process respectively. The maximum chaotic basic oscillation frequency is over 2.82GHz. Compared with the publicly reported maximum fundamental frequency (1.60GHz), the total bandwidth of the frequency spectrum with continuous chaotic signals reaches 9.04 GHz, 0.56 GHz and 9.60 GHz, and the bandwidth of the continuous spectrum within the power spectrum difference 10dB reaches 1.92 GHz 1.28 GHz 3.20 GHz 2.30 GHz 3.20 GHz 3.50 GHz 3.20 GHz 3.20 GHz 6.40 GHz 9.60 GHz.
【学位授予单位】：南京大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：O415.5;TM132

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