Analog blocks in telecommunications systems

Monolithic realizations of general telecommunications systems require high-performance internal circuits. To achieve these results digital and analog solutions are available. The general trend is toward digital implementations which guarantee high density and easy design. However, in each overall system there are some blocks requiring necessary an analog solution. Furthermore the entire system performance is often strictly dependent on the performance of the analog section. In this paper the role of analog blocks in three telecommunications systems (ISDN, line card and telephone set) is described.     

Building blocks for IP telephony

Convergence between the existing telephone networks and data transfer over the Internet not only demands that new software be written to handle telephony applications which span both networks, but also makes new and innovative applications possible. Rather than writing these applications from the ground up, it would be helpful to have a relatively high-level API on which to prototype new applications. In this article we describe a set of Java packages developed at Cornell University to accomplish this purpose. The software's name is ITX; it is available for download at no charge, and includes sample applications and documentation     

SJ/Z 11354-2006《集成电路模拟/混合信号IP核规范》概要

本指导性技术文件是在参照VSIA(Virtual Socket Interface Aliiance)《Analog/Mixed-Signal VSI Extension Specification Version 2.2》的基础上制定的,并得到了VSIA的版权许可.     

SJ／Z 11354-2006《集成电路模拟／混合信号IP核规范》概要

本指导性技术文件是在参照VSIA（Virtual Socket nterface Alliance）《Analog／Mixed—Signal VSI Extension Specification Version 2．2》的基础上制定的，并得到了VSIA的版权许可。     

Analog CMOS building blocks for custom and semicustom applications

Standard analog building blocks developed for use in custom and semicustom LSI and VLSI designs are described. The analog blocks are built using a digital CMOS process modified to include high-value resistors and voltage independent capacitors. Designs for operational amplifiers, programmable voltage sources, comparators, bandgap voltage references, unit resistors, capacitors, and n-p-n devices are discussed. Performance characteristics including unity-gain bandwidth, output drive, output impedance, and common mode range are reviewed. MOS noise data, subthreshold operation, and device matching are analyzed. Layout guidelines are proposed as well as applications and limitations of the analog building blocks.     

Analog reflection topology building blocks for adaptive microwavesignal processing applications

The synthesis and realization of an analog-phase shifter, delay line, attenuator, and group delay synthesizer-are presented. These variable control devices are all implemented using the same generic single stage reflection topology. The optimum conditions of operation have been determined and the corresponding group delay behaviors have been investigated to produce simple design equations. As proof-of-concepts, monolithic technology has been used to realize an X-band, phase shifter, delay line, and attenuator. Hybrid technology has been used to realize an L-band, group-delay synthesizer. Because of the high levels of performance measured, these control devices are ideally suited for use as general building blocks in adaptive signal processing applications, including large phased array applications     

带串行输出接口的A/D转换器TLC1549IP及其应用

文章介绍了带串行输出接口的A／D转换器TLC1549IP的基本工作原理，给出了它的接口时序，同时对其量化误差进行了分析。从实际应用出发，文中还给出了TLC1549IP与通用PC机连接的接口电路和接口程序。     

IP switching-ATM under IP

Internet protocol (IP) traffic on the Internet and private enterprise networks has been growing exponentially for some time. This growth is beginning to stress the traditional processor-based design of current-day routers. Switching technology offers much higher aggregate bandwidth, but presently only offers a layer-2 bridging solution. Various proposals are under way to support IP routing over an asynchronous transfer mode (ATM) network. However, these proposals hide the real network topology from the IP layer by treating the data-link layer as a large opaque network cloud. We argue that this leads to complexity, inefficiency, and duplication of functionality in the resulting network. We propose an alternative in which we discard the end-to-end ATM connection and integrate fast ATM hardware directly with IP, preserving the connectionless nature of IP. We use the soft-state in the ATM hardware to cache the IP forwarding decision. This enables further traffic on the same IP flow to be switched by the ATM hardware rather than forwarded by IP software. We claim that this approach combines the simplicity, scalability, and robustness of IP, with the speed, capacity, and multiservice traffic capabilities of ATM     

如何降低音频功率放大器瞬时杂音

TPA1517音频功率放大器是一款功能强大的通用器件,能够将6 W以上的立体声功率输入到低至4W的负载中.但是TPA1517存在一个现象,即当器件从待机模式退出时会听到令人不快的"噼噗"声.本文能够帮助电路设计师更好地了解什么是瞬时杂音,为什么这种器件会出现这种现象,瞬时杂音抑制电路(pop-reduction circuit)为什么能发挥作用,以及在此电路中使用不同组件会出现怎样的利弊.     

移动IP与蜂窝IP技术

人们对以无线方式接入Internet的需求日益增长。首先介绍了移动IP（Mobile IP）的基本原理，并指出其在支持微移动性方面的不足。然后详细介绍和分析了蜂窝IP（Cellular IP）的概念及路由、寻呼和切换等关键技术。最后根据这两种技术的互补性，提出二者进行无缝结合的方案，并认为这种结合将成为未来移动互联技术的发展方向之一。     

IP switching for scalable IP services

Internet protocol (IP) switching is emerging as a critical technology for improving the speed and scalability of the Internet. This paper discusses IP Navigator, a form of IP switching developed specifically for use in core network backbones, such as Internet service provider networks and major corporate backbones. IP Navigator combines the high speed and quality of service capabilities of asynchronous transfer mode (ATM) with the scalability and flexibility of IP. This paper presents an overview of the techniques that have been developed for operating IP over ATM. We outline the IP Navigator design and compare IP Navigator with other IP switching approaches     

移动IP与蜂窝IP的结合

文章介绍了一种将移动IP与蜂窝IP相结合（MIP-CIP）的系统，用仿真的方法分析了移动节点在CIP网络内部移动和网络间移动时的服务质量（QoS）性能指标，提出并比较了MIP-CIP应用的2种方案。     

Analog Switches in Programmable Analog Devices: Quiescent Defective Behaviours

Analog Switches (AS) play an essential role in a large number of Mixed-Signal circuits. Depending on the use of AS, designers have optimised their topology to meet the needs of each specific switching function. Furthermore, the success of Field Programmable devices in the digital domain (FPGAs) has motivated some manufacturers to explore similar solutions to fast prototype in the Analog and Mixed Signal domains. In this work, we explore the defective behaviours of programmable AS under realistic catastrophic and parametric defects. A classification of the DC defective behaviours for bridging and open defects is presented. This classification shows that the simple fault model with faulty state of permanently transistor stuck-on or stuck-off is not sufficient to reflect the real behaviour of a defective switch. It has also been found that parametric defects such as threshold voltage variations are not DC testable, and would therefore require additional AC tests.     

Combined Analog and Digital Error-Correcting Codes for Analog Information Sources

This paper focuses on error-correcting codes for analog signals. Generally, error-correcting codes exhibit a threshold effect, which degrades performance at the low signal-to-noise ratio (SNR) range. We propose two error-correction alternatives based on chaotic dynamical systems, which improve threshold performance relative to previously proposed methods. The first one, which is based on principles of diversity, exhibits a very simple decoder. The second alternative, which is based on a low-density parity-check (LDPC) code, attains a significantly lower threshold. Theoretical analysis and simulations are provided.     

Integrated-Circuit Analog Multiplexer

An analog multiplexer which allows several data channels to share the available bandwidth of one channel of an analog tape recorder is described. The method involves demodulation by correlating with a separately recorded carrier. Inexpensive integrated circuits are the only active elements.     

Analog sample-data filters

An analogue sample-data filter exactly equivalent, in the sample- data limit, to a simple RC low pass filter is demonstrated. The implementation requires only capacitors, MOSFETS, and a pulse generator. The filter time constant can be adjusted by changing the generator's pulse rate. The basic concept is then extended to apply to high-pass and to very-high-Q bandpass filters.     

集成模拟乘法器

本文简述了集成模拟乘法器的作用与实现方法及各种方法的优缺点。着重介绍了开关模拟乘法器和四象限模拟乘法器的组成、工作原理、发展状况、主要特点和用途。详述了国外新产品ＨＰＭＸ２００１型硅双极单片ＱＰＳＫ调制器；列举了ＡＤ５３２内修正集成电路乘法器／除法器和ＡＤ５３４高性能内修正集成电路四象限乘法器／除法器的主要性能；指出研制正文电路及四象限乘法器的必要性和技术要求。     

声频模拟分配器

广播音频系统设备的源阻抗和负载阻抗一般定为600Ω,设备和设备在作各种不同用途的连接时,必须进行接口设计,才能保持设备的优良特性和获得良好的系统指标。不正确的接口,会导致失真、噪声、频响、输出电平等特性的严重恶化。我们综合广播音频设备的特点及应用电压匹配技术的原理而设计的声频模拟分配器,是一种多功能的接口设备,它的应用使连接十分方便。