A Modified Equal-Element Band-Pass Filter

A method is presented whereby considerable improvement in the frequency response of a five-stage, equal-element waveguide filter can be realized while preserving nearly all the structural simplicity of this realization. It is shown that by increasing the loaded Q of the center resonant element of a five-stage, equal-element filter, the pass band ripple can be appreciably reduced and the skirt selectivity improved. The modified design also provides a simple means of bandwidth adjustment.     

Comment: Multifunction Current Differencing Cascaded Transconductance Amplifier (MCDTA) and Its Application to Current-Mode Multiphase Sinusoidal Oscillator

The intention of this letter is to draw the attention of journal as well as all the readers towards the duplication so that the reputation of the journal and ethics in the research could be maintained.     

Current Differencing Cascaded Transconductance Amplifier (CDCTA) and Its Applications on Current-Mode nth-Order Filters

In this paper, a new active device, current differencing cascaded transconductance amplifier (CDCTA), has been presented. The proposed CDCTA simplifies the design of the current-mode filter circuit considerably, especially the design of high-order filter. Moreover, a current-mode nth-order filter based on the CDCTA is proposed in the paper. The proposed circuit, which adopts only an active component and n grounded capacitors, contains minimal active component and passive one. It enjoys the simple configuration and is suitable for integrated circuit (IC) fabrication. PSpice simulations for current-mode third-order filter based on this structure have also been conducted, and the results are in good agreement with the theoretical analysis. The influences of the CDCTA non-idealities are also discussed.     

基于运放的电流模式滤波电路TT结构分析

本文提出了以基于运放Op-Amp的电流积分器为基础,构成有源RC电流滤波电路MOSFET－C（TT）结构。对这种电流模式TT结构进行了深入的理论研究,并利用PSPICE通用模拟电路程序,对其输出电压幅频特性和相频特性进行了仿真分析。得出了几点实用的结论。     

电流模式N阶CCCII(±)-C低通滤波器的系统设计

提出了一种基于多输出电流控制传送器(multiple outputs current controlled conveyor II,CCCII±)的多环反馈电流模式n阶低通滤波器的系统设计方法.用该方法可产生出多种不同结构的n阶低通滤波器.所有n阶滤波器均由 个CCCII±及n个接地电容组成.面向实际电路,完成了PSpice仿真,结果表明所提出的电路方案正确有效.     

几何布鲁姆过滤器的设计与分析

针对经典计数型布鲁姆过滤器( NCBF)存储和查询性能较低的缺陷,提出了几何布鲁姆过滤器结构GBF.该结构通过引入“哈希指纹”、布鲁姆过滤器两次分割、基于桶负载存放的方法,实现了集合元素的简洁存储、快速查询.基于“微分方程”和“概率论”的相关知识,对GBF模型进行了理论分析和求解,建立了错误概率和计算复杂度的关系表达式,论证了GBF的几何分布特性.仿真结果表明:与NCBF相比,GBF具有较低错误概率和计算复杂度的同时,也能保持较高的空间利用率.     

光学新事物滤波器及其应用

光学新事物滤波器是一种光子学器件,只显示与输入图像相比新出现的或者是有变化的部分,而静止的图像部分在输出图像中不被显示.光学新事物滤波器被广泛用于探测和跟踪移动的物体,相位测量以及生物医学等方面.新事物滤波器所用的材料目前有两大类:一类是无机晶体,主要是钛酸钡晶体以及掺杂的钛酸钡晶体;另外一类是有机光学材料,包括各种光折变聚合物和生物光子学材料细菌视紫红质等.介绍了各种新事物滤波器的工作原理以及在各个领域的应用.     

Analytical Synthesis of Current-Mode High-Order Single-Ended-Input OTA and Equal-Capacitor Elliptic Filter Structures With the Minimum Number of Components

None of the previously reported third-order and fourth-order operational transconductance amplifier and capacitor (OTA-C) elliptic filter structures use the minimum number of active and passive components. After an innovative algebraic decomposition for a complicated transfer function, i.e., a new analytical synthesis method, a current-mode odd-nth-order and a current-mode even-nth-order OTA-C elliptic filter structure having the following advantages are presented: 1) all the OTAs have single-ended inputs; 2) all the capacitors are grounded; 3) the minimum active and passive components are used. An equal-capacitance-type structure is designed taking into account the difficulty of precisely fabricating capacitances in integrated circuits. Although the above three advantages lead to the lowest total parasitics and to the most precise output response, the small deviations (such as the 3.5159% error in f_p) of the four parameters of the new third-order OTA-C elliptic filter can be drastically reduced (for example, to 0.1553% error in f_p) by only slightly tuning the four transconductances, but fixing the ratio of the given three capacitances, and without adding any other active and passive components. H-spice high-pass and low-pass simulations with 0.35-mum process are provided to demonstrate the theoretical results.     

改进的Huffman编码及其应用

该文探讨了JPEG压缩技术，重点针对Huffman编码中最优二叉树的“形态”不唯一问题，提出一种基于“简单原则”的新方法。经过这种方法改进的Huffman编码，使得JPEG中相应的值或字符的Huffman编码是唯一的。与传统的Huffman算法及近年来国内外文献中提出的改进算法相比，该方法编码步骤和相关操作更简洁，因而更利于程序的实现和移植。最后给出一个实例，表明此方法的实用性。     

The IMCON Pulse Compression Filter and Its Applications

The IMCON is a reflection-mode dispersive delay line capable of high performance in large time-bandwidth product pulse compression systems. As developed in this paper, the unique characteristics of the IMCON are obtained by reflection from a double grating array that is applied to the surface of a strip. Current models of the device have center frequencies in the 4-30-MHz range with bandwidth up to 15 MHz, dispersion to 320 /spl mu/s time sidelobes on the order of --40 dB (with equalization), and other spurious signals at least 70 dB below the compressed output. The characteristics of IMCON operation are developed from a consideration of the device's transfer function. In particular, the IMCON'S high linearity and low sensitivity to fabrication and propagation problems are shown to be due to a unique error rejection effect. By comparison, the error rejection characteristics of single grating and dispersive transducer devices are found to be inferior to the IMCON. Data derived from operating pulse compression systems are utilized to demonstrate the low time sidelobe and high time-bandwidth capability of the IMCON.     

一种改进的自适应格型陷波算法及其收敛性分析

现有自适应格型陷波器中的引入算子取自局部误差信号,在迭代过程收敛后存在陷波频率偏移的问题,影响了滤波的效果.本文对级联格型陷波滤波器的自适应算法进行了讨论,分析了陷波参数估计与引入算子的关系,在推导原算法迭代误差的数学期望方程基础上,提出一种改进的自适应滤波算法.该算法在不增加计算量的前提下,克服了原算法在收敛后存在的陷波频率偏移的不足.仿真结果与理论分析相一致,证实了该算法的收敛性能优于原有的算法.     

一类形态带通滤波器及其特性分析

本文利用数学形态学中的开运算构成了一类形态带通滤波器，并且入地分析了它们的性质，这类滤波器只允许图像中具有特定形状的物体通过，因而能够有效地用于抽取图象的形状特征。     

WiMAX and Its Applications (1)

WiMAX, an emerging broadband radio access technology, has attracted much attention from the whole telecom industry in recent years. Its main features are the high-speed transmission rate, large coverage, support for mobility, QoS guarantee and all-IP architecture. The technology fulfills the integration of packetized data, broadband access and mobillized terminal therefore, it has a bright future for wide application. This lecture will discuss WiMAX in four parts. This part will introduce the main features of WiMAX and IEEE 802.16 standards, the protocol structure, and the basic characteristics and key technologies for the physical layer. In the next three parts, the MAC layer and its QoS mechanism, WiMAX network architecture, WiMAX applications, and the development tendency of WiMAX will be discussed.     

WiMAX and Its Applications (3)

Worldwide Interoperability for Microwave Access (WiMAX), an emerging broadband radio access technology, has attracted much attention from the whole telecom industry in recent years. Its main features are the high-speed transmission rate, large coverage, support for mobility, QoS guarantee and all-IP architecture. The technology fulfills the integration of packetized data, broadband access and mobilized terminal; therefore, it has a bright future for wide application. This lecture discusses WiMAX in four parts, and this part introduces QoS mechanism of the MAC layer and the WiMAX network architecture.     

WiMAX and Its Applications (4)

Worldwide Interoperability for Microwave Access (WiMAX), an emerging broadband radio access technology, has attracted much attention from the whole telecom industry in recent years. Its main features are high-speed transmission rate, large coverage, support for mobility, QoS guarantee and all-IP architecture. The technology fulfills the integration of packetized data, broadband access and mobilized terminal; therefore, it has a bright future for wide application. This lecture discusses WiMAX in four parts, and this part introduces QoS mechanism of the MAC layer and the WiMAX network architecture.     

WiMAX and Its Applications (2)

Worldwide Interoperability for Microwave Access (WiMAX), an emerging broadband radio access technology, has attracted much attention from the whole telecom industry in recent years. Its main features are the high-speed transmission rate, large coverage, support for mobility, QoS guarantee and all-IP architecture. The technology fulfills the integration of packetized data, broadband access and mobilized terminal; therefore, it has a bright future for wide application. This lecture discusses WiMAX in four parts, and this part introduces the MAC layer and its QoS mechanism.     

Angular Bend Half Mode Substrate Integrated Waveguide (HMSIW) Based Band-Pass Filter with Multiple Transmission Zeroes

Wireless Personal Communications - Design methodology of 90° bend half mode substrate integrated waveguide (HMSIW) band pass filter (BPF) is presented in this paper. Edge wall reflections...     

网格技术及其应用1

网格(Grid)是构筑在Internet上的一组新兴技术,可将高速互联网、电脑、大型资料库、传感器、远端设备等融为一体,提供更多功能及服务.网格除了能为人们提供共享运算、存储及其他资源外,还可提供包括通信、软件、信息硬件及相关知识等资源.本讲座将分3讲对网格技术进行介绍:第1讲介绍网格技术的基本概念,如网格的定义,网格的组成和特征;还介绍部分网格的体系结构,如5层沙漏结构.第2讲继续介绍网格的体系结构,如开放网格服务体系结构以及其支撑工具--Globus.第3讲介绍网格实现技术及网格技术在相关行业的应用.     

网格技术及其应用(3)

网格(Grid)是构筑在Internet上的一组新兴技术,可将高速互联网、电脑、大型资料库、传感器、远端设备等融为一体,提供更多功能及服务.网格除了能为人们提供共享运算、存储及其他资源外,还可提供包括通信、软件、信息及相关知识等资源.本讲座第1、2讲分别介绍了网格技术的基本概念,如网格的定义、网格的组成和特征;网格的体系结构,如5层沙漏结构、开放网格服务体系结构以及其支撑工具--Globus;本期将介绍网格实现技术及网格技术在相关行业的应用.     

Direct Coupled Coaxial and Waveguide Band-Pass Filters (Correspondence)

In this note, experimental results will be presented for practical coaxial and waveguide band-pass filters. Filters of both types were originally developed in the 1700 Mc to 2300 Mc frequency range for application in a wide-band microwave radio relay communications system. The specifications for these filters called for very low input VSWR's over an appreciable part of the filter pass bands. This is necessary to minimize the degradation in system performance due to intermodulation noise resulting from feeder distortion of microwave transmission lines and/or group delay distortion within the microwave filters. Both the coaxial and waveguide band-pass filters employed five direct coupled resonators. Filters were designed for Butterworth (maximally flat amplitude) response shapes and nominal filter 3 db bandwidths of 60 Mc