利用现有双绞铜线实现高速数据通信的HDSL和ADSL技术

本文详细论述了利用现有双绞铜线进行高速数据传输的最新技术ＨＤＳＬ和ＡＤＳＬ的发展概况，基本结构、关键技术和所能达到的性能及其前景。     

ADSL的线路调制技术

ＡＤＳＬ在线路调制无后采用过正交幅度调制，无载波幅度相位调制和离散多频调制。ＱＡＭ和ＣＡＰ在６Ｍｂ／ｓ以下的速率和中工作得很好，ＤＭＴ则在更高速率上表现出明显的优势。传统的ＤＭＴ系统采用ＩＤＦＴ和ＤＦＴ实现调制和解调，用散小波变换代替ＤＦＴ的ＤＷＭＴ系统可以获得更好的传输性能。     

ADSL的线路分析及测试

本文具体分析了现有铜缆线路影响ADSL的应用的几个问题，讲述了铜缆线路的测试原理，方法以及测试内容，最后介绍了ADSL测试仪表。     

用LT1886的ADSL Modems作远程、高速率的线路驱动器

介绍一款用LT1886的ADSL Modems作远程.高速率线路驱动器     

用LT886的ADSL Modems作远程、高速率的线路驱动器

介绍一款用LT1886的ADSL Modems作远程，高速率线路驱动器。     

影响ADSL线路质量因素的分析

本先简单介绍了ADSL技术的基本原理，然后分析了线路衰耗、码间干扰、反射干扰、串音干扰和噪声干扰等影响ADSL传输质量的因素，为ADSL实际使用中进行线路测试提供了参考依据。     

在双绞铜线上进行视频通信的ADSL技术

ＡＤＳＬ技术是在双绞铜线上进行视频通信的新技术。它采用ＤＭＴ编码等传输技术，可为现有的电话用户提供宽带业务。文章详细论述了ＡＤＳＬ的关键技术，基本结构，舆性能及其应用前景。     

浅析ADSL接入技术及提高铜缆出线率的措施

随着信息技术的飞速发展，技术的不断创新，市话电缆已不再是传统语音信号，本文重点介绍和分析了ADSL接入技术及其特点，针对市话电缆开通ADSL，如何提高铜缆出线率问题进行分析，并提出一些解决措施。     

线路驱动器EL 1508C在ADSL局端的设计与应用

本文主要介绍了ADSL局端设计的指标，DSL线路驱动器EL1508C的性能，并阐述了它在高密度ADSL的设计要点，最后给出了一款实用的EL1508C参考设计电路图。     

ADSL用户MODEM中驱动器的设计与实现

在分析用户MODEM驱动器特点的基础上,选定了驱动器的结构。说明了驱动器中各元件参数的设计方法，及各参数与驱动器性能的关系。最后给出了一种可实现的驱动器设计方案。     

VDSL与ADSL技术的比较

文章介绍了非对称数字用户线(ADSL)与甚高速数字用户线(VDSL)的关键技术，并对这两种数字用户线技术从调制技术、拓扑结构和应用环境等方面做了全方位的比较．     

ADSL、ADSL2、ADSL2＋以及VDSL的技术分析

作为通信网中与用户相连的“最后一公里”网络,接入网的主要功能是将语言、数据、图像等多种业务传送到用户。制约接入网发展的主要因素是接入的经济性问题,这与用户的业务需求、用户分布、用户的经济承受能力、接入技术等多方面因素密切相关。目前的主要宽带接入技术有:以电话铜缆为接入手段的xDSL技术;以五类双绞线为接入手段的以太网接入技术;以同轴电缆为接入手段的HFC技术;以无线为物理媒质的WLAN、LMDS和MMDS技术;以光纤为接入手段的宽带PON技术。目前来看,xDSL得到应用最多的是ADSL和VDSL技术。ADSL和VDSL技术都能利…     

用于VDSL的异步Σ-Δ调制D类线路驱动器设计

本文以30MHz带宽VDSL线路驱动器为设计目标,对1阶异步Σ-Δ调制(asynchronous sigma-delta modulation,ASDM)的D类线路驱动器进行了系统级设计,并在TSMC 0.25μm 3.3V CMOS工艺下完成了电路设计.对版图参数提取后仿真结果显示,在最慢工艺角(即ss工艺角)、125℃时,极限环频率可达到70MHz,在27MHz带宽内,输出信号幅值0.7V时的无杂散动态范围(SFDR)可达到63dBc.     

A Low-Distortion Class G Line Driver for Central-Office ADSL Modem

This paper presents the design of a high-efficiency line driver for central-office ADSL modems. This driveris a modification of the conventional class-G architecture already in use for hi-fi audio applications and it isbased on two amplifiers operating in parallel and powered by different power supplies (±5 V and±12 V). The low-voltage amplifier is active with low-level input signal, while the high-voltageamplifier is used for processing the peaks of the DMT signal. By means of this solution and by properly interfacingthe two amplifiers, high efficiency is achieved while maintaining a harmonic distortion similar to the one achievedby conventional class-AB schemes and compatible with the ADSL requirements. The circuit was designed in a 0.8-mBCD technology.     

The noise and crosstalk environment for ADSL and VDSL systems

This article provides an overview of the noise and, in particular, the crosstalk environment in which DSL technology needs to operate. Transmission on the copper access network is subject to impairments which limit the achievable information capacity, and there is an urgent need to ensure that all DSL systems are spectrally compatible if the capacity of the network is to be fully realized. This article discusses the principles of frequency planning in copper access networks that help to ensure compatibility of deployed systems     

极限环频率对自激振荡线路驱动器的影响分析

目前自激振荡线路驱动器由于极限环频率较低,在输入信号频率较高时,系统增益下降较大,由延时决定的自激振荡线路驱动器可提高极限环频率。本文分析了提高极限环频率后系统增益、线性度和功耗等的变化,并采用0.25μm CMOS工艺设计了一个VDSL线路驱动器进行验证。实验结果表明,提高极限环频率可减小高频输入信号时系统增益的下降,且在一定范围内可提高线性度,但过高的极限环频率会引入过大的电源噪声和地噪声,恶化线性度。     

Stress Mechanism about Field Lightning Surge of High Voltage BJT Based Line Driver for ADSL System

In this paper, we have verified stress root caused by lightning surge in High voltage BJT based line driver of ADSL telecommunication and created failure mechanism. To reproduce damages in Line driver, we have applied STD surge waveform in operating condition, which is specified in IEC-6000-4-5, to component and board level. Visual isolation for Damage root was conducted with Real-time Electrical Stress Analysis (RTESA) utilizing Photon Emission Microscopy (PEM). The surge made with input of Tx output created junction breakdown of amplifier, which is made of HVBJT cells, and also caused current crowding from Vcc (supply voltage). In case of Positive pulse, current crowding was observed from between Collector and Vcc (+)12V. For negative pulse, at between Emitter and Vee (−)12V, current crowding was found. For both cases, device damage level was the same. All of these could be considered as transient latchup phenomenon created in BJT cell. Applying temporary clamping diode to line driver Tx, we have conducted Board level surge injection test. As a result, with the correlation between surge level from component level reproduction test and the one from system level, we have decided field lightning surge damage level and set up line driver protection margin.     

Digital subscriber line (HDSL and ADSL) capacity of the outsideloop plant

The fundamental limits of the outside loop plant to carry high-speed digital (bi-directional HDSL and ADSL) data are reported. The paper focuses on the copper wire pairs, drop lengths, and interconnects that convey data over the “last mile” to almost all businesses and residences in the US. The two major customers, businesses and households, are classified, characterized, and categorized by the distance to the central office or the remote terminal. Their spectral capabilities are computed and their ultimate digital capabilities are reported. The crosstalk limitations inherent in the plant are also computed and verified against the loss of signal due the distance and spectral constraints. The signal to noise ratio can thus be estimated to ascertain the transmission quality through the plant. Accordingly, the paper reports on losses, bandwidths, and bit rates in the first half, and discusses the major bottlenecks in the second half