采用磁集成技术的低压大电流DC/DC变换器的仿真

运用回转器一电容模型可以很好的理解磁性器件，特别是复杂的集成磁件。文章运用磁导电容类比建模法建立了磁件的回转器一电容模型。在回转器一电容模型中，磁路由容性电路来模拟，绕组由双端口的回转器来代替。进行了采用磁集成技术的低压大电流DC／DC变换器的仿真。仿真电路拓扑是原边不对称半桥、副边倍流整流电路。磁集成变压器的结构是Wei Chen提出的原边绕于中柱的只在侧柱开气隙的倍流整流磁集成结构。建立了用SPICE语言描述的回转器仿真模型。仿真软件是MULTISIM2001。     

网络函数矩阵的电路综合

提出了用(p+q)端口回转器综合网络函数矩阵的原理和方法,给出了网络函数矩阵系统综合电路.首先将网络函数(传输和混合函数)矩阵方程转换成多端口阻抗函数矩阵方程,然后,将多端口阻抗函数矩阵Z(s)分解成G·Yb(s)·GT的形式,实现了Z(s)=G·Yb(s)·GT的电路综合.并且给出了求函数矩阵Yb(s)和矩阵G的方法.     

Single transistor high linearity and wide dynamic range active inductor

In this paper, an active inductor (AI) with high linearity and high dynamic range, including a minimum number of components, is presented. The AI is composed by a single transistor, and by a passive compensation network; the latter allows the control of the values of both the inductance and the series resistance. In order to show the feasibility of the proposed AI for filter applications, a prototype board on a TLX8 substrate with a first‐order active band‐pass filter has been fabricated and tested. The filter has a center frequency of 2470 MHz (useful for Bluetooth applications) and a measured noise figure (NF) of 9 dB with a ?5 dBm P₁dB compression point, and a 75 dB dynamic range. Copyright © 2013 John Wiley & Sons, Ltd.     

基于单个CCCCTA接地回转器的系统综合

为综合基于CCCCTA的接地回转器,根据CCCCTA的零-镜模型和接地回转器的节点导纳矩阵,利用节点导纳矩阵扩展法,我们实现了4个相互等效的接地回转器。导出的回转器具有两个特点,一个是通过调节CCCCTA的偏置电流,可以电控调节回转器的参数; 另一个特点是电路仅使用单个CCCCTA。作为一个例子,通过使用导出的回转器之一,我们实现了一个极点频率为1.274MHz、品质因素为4的带通滤波器。计算机仿真证明所导出的电路正确有效。     

晶体管工作状态对SiGe带通滤波器的影响研究

采用SiGe异质结双极晶体管,设计了一种具有回转结构的带通跨导-电容滤波器.使用ADS软件进行电路图的仿真分析.研究镜像电流源的集电极电阻R对该滤波器中心频率、输出增益及功耗的影响.分析结果表明,镜像电流源集电极电阻R的调节可以控制镜像电流源的晶体管工作状态和回转电路的偏置电流.因此,要获得更高的中心频率,镜像电流源中直接给跨导单元提供电流的晶体管不用按常规工作在放大区而可以工作在饱和区.对滤波器输出增益和功耗的进一步分析结果表明,以上晶体管工作在饱和区不仅可以提高滤波器的工作频率,还可以提高滤波器的输出增益,但是也会同时增加滤波器的功耗.     

gyrator变换域的高鲁棒多图像加密算法

目的 随着互联网通信和多媒体技术的快速发展,单幅图像加密技术难以满足日益增长的数据传输需求。为提高图像加密系统的传输效率,同时保证安全性和鲁棒性,本文构建一种基于gyrator变换和多分辨率奇异值分解（multi-resolution singular value decomposition,MRSVD）的多图像加密算法。方法 首先,将明文图像每两幅组合为复数矩阵,利用改进的logistic映射生成混沌相位掩模,对复数矩阵进行gyrator域的双随机相位编码。其次,将变换后矩阵的实部分量和虚部分量组合为实数矩阵并进行多分辨率奇异值分解。最后,使用正交系数矩阵对多分辨率奇异值分解的结果进行线性组合得到密文图像。结果 实验结果表明,使用本文算法得到的解密图像的峰值信噪比大于300 dB,解密图像质量相较于对比算法的解密图像质量更好;密钥发生微小改变前后密文相关系数（correlation coefficient,CC）远小于0.20,明文像素值发生微小变化时像素变化率（number of pixels change rate,NPCR）与归一化平均变化强度（unified average changing intensity,UACI）分别约为0.999 0和0.333 7;密钥空间大小为5.616 9×10⁶⁰,可以抵御蛮力攻击;当密文图像受到一定强度的高斯白噪声和剪切攻击时,本文算法能够较好地恢复明文图像。结论 所提出的多图像加密算法在高质量恢复明文图像的同时具有较高的安全性和较强的鲁棒性,可以应用于图像的内容保护与安全传输。     

一种基于Π形电路的回转器设计方法

提出了一种基于Π形电路的回转器实现电路的设计方法。该方法通过将电压控制电压源与电阻串联的支路并联接入Π形电路,利用运放电路来实现负电阻和受控源,给出了一种回转器实现电路的设计过程。给出了设计实例和Multisim电路仿真结果,表明本文方法的有效性。所讨论方法易于理解且具有普遍性,对于回转器以外的其它特定二端口电路的设计也具有一定的启发意义。     

Design methodology for common‐mode stability of OTA‐based gyrators

This paper presents a design methodology for common‐mode (CM) stability of operational transconductance amplifier (OTA)‐based gyrators. The topology of g_m ? C active inductors is briefly reviewed. Subsequently, a comprehensive mathematical analysis on the CM stability of OTA‐based gyrators is presented. Sufficient requirements for the gyrator's CM stability, which easily can be considered during the design process of common‐mode feedback (CMFB) amplifiers, are defined. Based on these stability requirements, a design methodology and a design procedure are proposed. Finally, in order to validate the proposed procedure, a resonator with 20 MHz resonance frequency and a quality factor of 20 is fabricated with UMC 180 nm complementary metal‐oxide‐semiconductor technology, and its CM stability is examined. Copyright © 2015 John Wiley & Sons, Ltd.     

Multiple color-image authentication system using HSI color space and QR decomposition in gyrator domains

Abstract

A new multiple color-image authentication system based on HSI (Hue–Saturation–Intensity) color space and QR decomposition in gyrator domains is proposed. In this scheme, original color images are converted from RGB (Red–Green–Blue) color spaces to HSI color spaces, divided into their H, S, and I components, and then obtained corresponding phase-encoded components. All the phase-encoded H, S, and I components are individually multiplied, and then modulated by random phase functions. The modulated H, S, and I components are convoluted into a single gray image with asymmetric cryptosystem. The resulting image is segregated into Q and R parts by QR decomposition. Finally, they are independently gyrator transformed to get their encoded parts. The encoded Q and R parts should be gathered without missing anyone for decryption. The angles of gyrator transform afford sensitive keys. The protocol based on QR decomposition of encoded matrix and getting back decoded matrix after multiplying matrices Q and R, enhances the security level. The random phase keys, individual phase keys, and asymmetric phase keys provide high robustness to the cryptosystem. Numerical simulation results demonstrate that this scheme is the superior than the existing techniques.