Multifunction CM/VM Biquads Realized with a Single CFOA and Grounded Capacitors

New configurations are proposed which realise multiple-input-single-output-type multifunction current mode and voltage mode biquads capable of realizing the low-pass, band-pass, high-pass, and notch functions from the same configuration using only a single current feedback op-amp, four resistors and two grounded capacitors. The new circuits offer several advantageous features over the previously known single-current feedback op-amp/second generation current conveyor-based biquads. Electronic tunability of ω_o is feasible by replacing the resistors by appropriately-valued CMOS voltage-controlled-resistors driven by a common external control voltage. PSPICE simulation and hardware implementation results are given which have demonstrated the workability of the proposed configurations.     

Lossless Inductor Current Sensing Method With Improved Frequency Response

The lossless inductor current sensing method is well-known and is frequently applied in the measurement of output current in DC-DC converters due to its low cost and simplicity. This technique uses a low-pass filter that is matched to the inductance (L) and winding resistance to compensate for induced voltages due to the inductor. However, the waveform fidelity above the corner frequency of the inductor is generally poor due to large production tolerances and thermal drift. In this letter, we propose the use of a coupled sense winding, which increases the corner frequency of the sensing circuit by more than two orders of magnitude. We show, as an example, that for a 3.85 muH inductor the corner frequency of the measurement circuit can be increased from 36 Hz using the conventional approach to 5.8 kHz using the coupled sense winding method. Above the new corner frequency, a low-pass filter is still required but may now be constructed using a smaller capacitor and with improved high-frequency response.     

从有损到无损的音频编解码框架

无损音频编码技术是用于数字音频数据存档,高质量音频编码的一种重要技术,提出了一种兼容有损编解码器的无损音频编解码系统设计。包括通过有损编码残差进行无损扩展和独立的无损编解码两部分。系统采用了声道去相关、整型提升小波、线性预测、残差处理和算术熵编码等技术。在相当复杂度条件下,达到与国际主流无损音频编码技术相当的压缩性能。     

基于整数小波变换的有损与无损嵌入式图像压缩

提出了基于整数小波变换的嵌入式图像编码方案，能够进行有损和无损两种模式的图像压缩，在非常低的比特率时能够获得较高质量的重构图像。该方法适合图像的渐进传输，它是使用扩增的零树信号和位面编码的合成技术，最后对产生的符号流进行算术编码。文中给出了该方法与有损和无损压缩标准的性能比较。     

Bidirectionality of Reciprocal, Lossy or Lossless, Uniform or Periodic Waveguides

Using the scattering-matrix equations for two antennas placed in the fields of a waveguide, it is proven that all reciprocal, lossy or lossless, uniform or periodic waveguides are bidirectional. Since Maxwell's equations imply directly that propagation constants on a lossless reciprocal waveguide come in pairs (beta,-beta*), "complex waves" on a lossless reciprocal, uniform or periodic waveguide come in quadruplets with propagation constants (beta,-beta, beta*,-beta*).     

A Novel Grounded Inductor Realization Using a Minimum Number of Active and Passive Components

In this study, we present a new topology for realizing a grounded inductor employing only a single current conveyor, called a negative‐type modified inverting second‐generation current conveyor (MICCII‐), and a minimum number of passive components, two resistors, and one capacitor. The non‐ideality effects of the MICCII‐on a simulated inductor are investigated. To demonstrate the performance of the presented inductance simulator, we use it to construct a third order Butterworth high‐pass filter and a parallel resonant circuit. Simulation results are given to confirm the theoretical analysis.     

一种基于抽头电感的分布式放大器

采用0.18 μm CMOS工艺,设计了一种基于抽头电感的四级分布式放大器。采用抽头电感,减小了片上电感的数量,减小了芯片面积,在保持良好的端口阻抗匹配特性的同时提升了分布式放大器的增益。仿真结果表明,在1.48~15.5 GHz频带范围内,增益为8.6 dB,波动程度为±1.25 dB。版图面积为(0.59×1.1) mm²。     

基于PLC的船舶车钟模拟装置设计

文章设计了一种基于PLC控制的船舶车钟模拟装置, 详细说明了其硬件选型及电路设计, 并进行了系统的软件及人机界面设计, 可以为内河船舶或小型电推船舶车钟控制系统设计提供借鉴。     

基于SPIHT算法的医学图像无失真压缩

提出了一种第二代小波变换与SPIHT算法相结合在图像无损压缩中的编／解码方案，给出了本方案的实验结果及与其他方法的压缩性能比较，研究表明这一方法对于医学图像具有较高的无损压缩率。     

The Treatment of Thin Wire and Coaxial Structures in Lossless and Lossy Media in FDTD by the Modification of Assigned Material Parameters

It has been shown recently that the use of modified assigned material parameters (MAMPs) within the finite-difference time-domain (FDTD) method provides a systematic, readily extensible, accurate, and efficient approach to the electromagnetic analysis of microstrip structures. In this paper, it is shown that this technique can also be applied with equal effect to lossless and lossy coaxial lines, wires in a lossy medium such as earthing grids, and more complex structures which include coaxial feeds and shorting posts. The modified parameters are calculated directly from the known asymptotic fields near the wire and do not rely on the concept of "equivalent radius." Results are given which show equal or superior performance compared to those obtained using other methods but with the added advantage of flexibility and rigor     

基于像素交换的无损信息隐藏

提出一种无损信息隐藏方法,接收端不但可以提取额外嵌入的秘密信息,而且可以无损恢复原始图像。该方法利用了相邻像素变化趋势往往一致的特性,对刻划这种特性的数据进行压缩以产生冗余空间用于携带额外的秘密信息,并使用像素值互换操作将额外信息及用于图像恢复所需数据一同嵌入到载体图像中。由于该方法顾及了人眼视觉特性,仅将数据嵌入在纹理区域,因此含密图像具有较好的视觉效果。     

TM and TE Mode Surface Waves on Grounded, Anisotropic, Inhomogeneous, Lossless, Dielectric Slabs (Correspondence)

J. H. Richmond has given the WKB solutions for the field distribution of surface waves on inhomogeneous, isotropic, plane layers. It is the purpose of this letter to extend his work to include a simple anistropy in the dielectric constant by considering a diagonalized relative permittivity tensor with components /spl epsi//sub x/(x), /spl epsi//sub y/(x), and /spl epsi//sub z/(x). The geometry is the same as before except that a perfectly conducting plane is now positioned at x = 0. For easy reference we have used the same notation as Richmond, except where specified otherwise. Compactness in notation has been achieved by expressing the integrations from 0 to x and by considering the x variations outside the slab to be exp {-a(x-a)}.     

一种基于键合线电感的LC-VCO设计方法

提出一种利用键合线电感设计VCO的方法,利用HFSS(High Frequency Structure Simulator)软件,建立电感仿真模型,在5 GHz以下与库模型相吻合.仿真结果表明,差分键合线电感受工艺偏差的影响小于15%,并提出一种减小互感的方式,使电感值在1～5 GHz范围内增加15%～175%.利用HFSS提取的等效电路,设计了一款输出频率为2～3.6 GHz的宽带压控振荡器(VCO),当工作在3.6 GHz时,1 MHz频偏处的相位噪声为-111 dBc/Hz,电流为1.5 mA.电路版图面积仅为0.1 mm2,较之采用片上电感的VCO(0.19 mm2),面积减小45%.     

基于Youla无耗均衡器的精确设计与仿真

以低通Butterworth 20MHz无耗均衡器的设计为例．为了解快通信系统的耦合网络问题，使用宽带匹配网络均衡电阻性信号源和频变负载，以获得预先规定的变换器功率增益特性。用Matlab和PSpice软件进行科学计算和电路仿真，设计出最佳宽带匹配网络，对现代通信系统具有重要意义。     

低压低功耗CMOS电流运算放大器的设计

设计了一种新型CMOS电流反馈运算放大器结构,通过在输出端采用电阻反馈,增强负载能力,利用MOS管实现串联电阻以消除补偿电容带来的低频零点.使用0.5 μm CMOS工艺参数,PSPICE模拟结果获得了与增益关系不大的带宽.电路参数为:80.7 dB的开环增益,266 MHz的单位增益带宽,62°的相位裕度,149 dB共模抑制比以及在1.2 V电源电压仅产生0.82 mW的功耗.     

一种基于图像的无损隐秘传输方法

提出了一种新的基于预测编码的图像无损隐秘传输方法.该方法用线性预测误差扩展和嵌入/提取算法,在图像无损编码压缩过程中嵌入大数据量的秘密信息,提取秘密信息后,原宿主图像信息能无损恢复.该方法已在局域网上进行了实验,结果表明,与以往的无损嵌入算法相比,其提高了秘密信息的可嵌入容量,且对隐藏信息后的图像质量影响较小.     

一种基于有耗传输线的动态Smith圆图

基于微波有耗传输线的基本模型,提出了一种针对实际传输线的动态Smith圆图;给出了该圆图详细的推导过程,并通过Matlab对该动态圆图进行了仿真;详细分析了该圆图的特点。该动态圆图完整地包含了阻抗和导纳两个部分,方便于解决微电子中的射频设计问题。     

基于LZW的多模式自适应的无损压缩算法

本文对LZW无损压缩算法的原理进行了剖析，并在此基础上研究出了一种多模式的、自适应的无损压缩算法。该算法经实验验证，和传统的LZW算法相比具有更高的压缩比和更好的自适应性。     

一种基于LTCC技术的螺旋电感带通滤波器

本文提出一种新型的基于低温共烧陶瓷技术(LTCC)的螺旋电感带通滤波器.滤波器的设计是利用螺旋电感的自谐振和谐振单元间的电磁耦合来实现.通过HFSS仿真和等效电路分析,对滤波器结构进行了优化分析.这种滤波器具有体积小.结构布局灵活的优点,可以很好的满足器件埋置的要求.     

电感器的特性及检测

电感器是三大基础元器件之一,在电路中有着非常重要的地位,它的应用有很多,对电感器特性的理解掌握正确的检测方法有着重要的意义。文章重点介绍了电感器的结构、特性功能和检测。