超隔离设计大功率UPS及其特性

结合一般非隔离UPS及超隔离设计UPS主回路拓扑结构，分析采用该两种结构的大功率UPS对于抗雷击、负载接地、传输噪音抑制、配电网络零线脱落故障等各种性能特点，指出采用超隔离设计的大功率UPS产品具有优异的应用特性。     

隔离型DC/DC在高压电压电流源设计中的应用

由于隔离型DC/DC的安全性、隔离性等特征,该类器件广泛应用于多个电子、工业领域,本文主要介绍了隔离型DC/DC在高压电压电流源中的应用。本文将隔离型双输出DC/DC引入设计,利用DC/DC的隔离特性,将电压电流源的次级输出作为DC/DC器件参考地,将DC/DC器件的两路输出电压作为相关运算放大器的电源电压。常规高压电压电流源设计中需要大量采用高压运算放大器,采用此方案可使用较少的高压运算放大器及更低的成本实现相同功能,同时降低高压电源对PCB电路板上信号的影响。通过实际测量,文中方案输出稳定、精度高,满足设计与使用要求。文中用功能图纸对此类应用进行了详细说明。     

带隔离电源的线性隔离放大器

带隔离电源的线性隔离放大器武汉工学院张菊秀干扰对计算机测控系统的影响，几乎是每个开发者都曾遇到过的问题。外界的各种干扰信号大多是以共模信号的形式通过信号线、电源、地线串人系统，影响其正常工作。因此要提高系统抗干扰的能力，必须解决防止干扰信号进人系统的...     

隔离式DC/DC转换器

ADuM6000采用10mm×10mm封装并集成ADI公司的专有iCoupler数字隔离技术和isoPower DC/DC转换器,其功率和隔离额定值分别为0.5和5kVrms。利用该新款数字隔离器,设计人员可以节省宝贵的电路板空间,且无须耗费大量时间去进行医疗或其他安全审批（如IEC-60601-1）。安全性是医疗和工业设计中的关键要求所在,而ADuM6000可以为器件和最终用户提供保护,     

隔离放大器AD210的应用

ＡＤ２１０是一种精确、宽带、三端隔离放大器。它能实现对输入、输出和电源的隔离，是目前隔离放大器中较为新颖的器件，本文主要介绍该芯片的特点和实际应用电路。     

支持时空隔离机制的微内核设计与实现

基于时空隔离的微内核设计思想能够满足安全关键嵌入式系统的非功能需求,给出了基于时空隔离机制的微内核系统架构设计,并对其时空隔离机制的实现给出了详细描述,并对微内核在嵌入式领域的应用进行了展望.     

大功率UPS超隔离设计及其应用特性

大功率UPS是区域重要负载设备的供电中心,其设计功能直接影响到对负载设备的供电品质及负载设备运行稳定性和可靠性。本文结合一般非隔离UPS及采用超隔离设计UPS主回路拓扑结构,分析采用此两种结构的大功率UPS对于抗雷击、负载接地、传输噪声抑制、配电网络中线脱落故障隔离等各种性能特点,指出采用超隔离设计的大功率UPS产品具有优异的应用特性。     

MORNSUN高隔离DC／DC转换器面市

MORNSUN公司新研发出3000VDC隔离非稳压单输出型输出功率为2W的DC／DC转换器-F_S-2W、F_D-2W。此系列产品体积极小，可靠性高，专为满足电力控制系统要求而设计的高隔离型DC／DC转换器，如网络电力仪表、智能电量变送器、传感器、隔离配电器、电量测控单元和配电自动化监控仪等产品，可为其提供安全可靠的隔离保护。     

物理隔离技术及其在政府网络中的应用

在当今网络信息安全的重要性日益凸现的现实环境下,政府等重要部门如何做好网络信息安全工作已成为一个重要的研究课题,物理隔离技术应运而生。物理隔离目前常见的实现方式以隔离卡和隔离集线器为主,实现多个网络的真正物理隔离。物理隔离作为一种更彻底、更安全的网络安全技术,在保密性要求较高的政府网络中得到了较广泛的应用。在实际应用中,为了弥补物理隔离技术的不足,还须将物理隔离和常规的网络安全技术结合起来,使网络信息安全得到最大的保障。     

浅谈数字通信接口的隔离技术

本文介绍了光耦隔离和iCoupler磁耦隔离器件的内部结构、功能特点以及在RS-232数字通信接口中的隔离应用,并对两种隔离技术进行了比较.     

Interference-rejection characteristics of biopotential amplifiers: a comparative analysis

The circuit parameters contributing to power line interference in ground-referenced, two- and three-electrode biopotential amplifiers, both isolated and nonisolated, are reviewed. The effects of external interference on different amplifiers are compared by using the 'effective coupling impedance' concept. Next, an analysis of the effect of imbalanced input impedances is carried out. It is concluded that the interference in an isolated amplifier is not always lower than in a nonisolated one, and that it must be reduced by an adequate sharing between the CMRR (common mode rejection ratio) and the IMRR (isolation mode rejection ratio); that an increase in common mode input impedance always reduces interferences in three-electrode amplifiers but not in two-electrode amplifiers; and that in two-electrode amplifiers, not only is the matching of input op amps important, but also the tolerance of components in first-stage circuits.<>     

A new modulation strategy for a buck-boost input AC/DC converter

This paper presents a novel modulation strategy for a power factor corrected (PFC), isolated AC/DC converter derived from the integration of a nonisolated, two switch buck-boost AC/DC converter with an isolated dual active bridge DC/DC converter (2SBBDAB). This strategy, termed discontinuous leading/trailing edge (DLTE) modulation, serves to maximize the duty cycle of the input switch while keeping the current in the buck-boost inductor discontinuous. Hence, the crest factors of the currents in the switching devices are minimized, the input switch is turned on at zero current and the zero-voltage switching ranges of the bridge switches are unaffected by the integration. A conventional isolated, PFC AC/DC converter typically consists of a boost converter cascaded with a forward converter. The ratings required of the power switching devices of the 2SBBDAB employing the DLTE modulation strategy are similar to those required of the conventional design for wide line voltage operation. However, the 2SBBDAB converter has higher line voltage surge immunity than that of the conventional design and, unlike the conventional design, it has inherent inrush current limiting. The DLTE modulation strategy may be applied to the family of converters composed of the two switch buck-boost integrated with half and full-bridge forward converters     

Soft switching active snubbers for DC/DC converters

A soft-switching active snubber is proposed to reduce the turn-off losses of the insulated gate bipolar transistor (IGBT) in a buck power converter. The soft-switching snubber provides zero-voltage switching for the IGBT, thereby reducing its high turn-off losses due to the current tailing. The proposed snubber uses an auxiliary switch to discharge the snubber capacitor. This auxiliary switch also operates at zero-voltage and zero-current switching. The size of the auxiliary switch compared to the main switch makes this snubber a good alternative to the conventional snubber or even to passive low-loss snubbers. The use of the soft-switching active snubber permits the IGBT to operate at high frequencies with an improved RBSOA. In the experimental results reported for a 1 kW, 40 kHz prototype, combined switching/snubbing losses are reduced by 36% through the use of the active snubber compared to a conventional RCD snubber. The use of an active snubber allows recovery of part of the energy stored in the snubber capacitor during turn-off. The generic snubber cell for the buck power converter is generalized to support the common nonisolated DC/DC power converters (buck, boost, buck-boost, Cuk, sepic, zeta) as well as isolated DC/DC power converters (forward, flyback, Cuk, and sepic)     

基于增量负载扰动和最小二乘拟合的通信电源效率测量法

为了克服传统的通信电源效率测量方法在实际操作中的困难,提出了一种基于增量负载扰动和最小二乘拟合的通信电源效率测量方法。对于工作在＂效率—输出负载电流＂曲线中段的通信电源,对其施加增量负载扰动,并运用最小二乘拟合去除测量中奇异点对结果的影响,最终得到通信电源的效率。本文列出了运用该方法测得的实验结果,并讨论了实验结果的相对误差。通过该方法也可以对通信电源的欠载或过载状态进行定性的判断。最后本文提出了该方法在通信电源规模生产的自动化测试中的应用。因此该方法是一种实用的新型通信电源效率测量方法。     

一种低功耗原边反馈AC/DC转换器

低待机功耗、高效率的绿色电源已成为未来电源技术发展的方向,国际上已经正式提出六级能效标准。提出了一种采用常规工艺实现的原边反馈AC/DC转换器电路,解决了传统原边反馈AC/DC转换器元器件多、待机功耗大以及用高压特殊工艺实现低待机功耗的成本昂贵等问题。该原边反馈AC/DC转换器能够满足六级能效标准。     

全光纤型Er/Yb共掺光纤短腔激光器

报道了一种高输出功率、高斜率效率的短腔ErYb共掺杂光纤激光器。激光谐振腔由一段ErYb共掺杂单模光纤与一对布拉格反射波长相同的光纤布拉格光栅(FBG)组成。反射率为60%的光纤光栅用作光纤激光器谐振腔的输出,3dB带宽为016nm。反射率为99%的光纤光栅作为高宽带反射腔镜,同时作为抽运光输入端,3dB带宽102nm。以980nm激光二极管(LD)作抽运源进行实验。使用不同的抽运功率分别测量不同长度的ErYb共掺杂光纤,优化光纤激光器谐振腔得到的最佳长度仅为13cm。即选用13cmErYb共掺杂光纤作为增益介质来制作短腔ErYb光纤光栅激光器,最大输出功率可达11mW,输出功率稳定性<±001dB,抽运阈值功率为35mW,斜率效率为153%,测量其15522nm激光的输出光谱,25dB线宽为03nm,边模抑制比>60dB,波长稳定性为005nm。可用于密集波分复用(DWDM)系统。     

Baseband and audio mixed-signal front-end IC for GSM/EDGE applications

A complete mixed-signal front-end CMOS chip is presented, supporting GSM/EDGE as well as enhanced audio applications. The chosen solution for the transmit section is based on Laurent's approximation of the nonlinear GMSK modulator. This enables burst shaping in the I/Q domain thereby solving the problem of power ramping. Also, up to GPRS class 12 is supported. The receive section on the other hand consists of a low power dual mode continuous-time /spl Sigma//spl Delta/ ADC for I and Q, supporting ZIF and LIF modes of operation and achieving typically 12.5 bit of resolution under production conditions. An on-chip PLL, which supplies all blocks with various clock frequencies, additionally supports clock jitter suppression. The audio section comprises a codec supporting standard formats such as IIS and PCM. It features mono/stereo signaling from various sources in 16bit quality as well as high-drive buffers for 4 /spl Omega/ single-ended loads (capacitively coupled). The whole chip is powered from a 1.5/2.65 V supply voltage and consumes 22 mW in paging mode.     

大功率GaAs/GaAlAs单量子阱激光器

采用MOCVD技术在φ40mmGaAs衬底上研制成大功率GaAs/GaAlAs单量子阱激光器。该激光器激射波长为830～870nm,室温CW阈值电流密度小于350A/cm~2,最低值为310A/cm~2,输出光功率大于200mW/(单面,未镀膜)。     

A 1-/spl mu/m Bipolar VLSI Technology

A 1-/spl mu/m VLSI process technology has been developed for the fabrication of bipolar circuits. The process employs electron-beam slicing writing, plasma processing, ion implantation, and low-temperature oxidation/annealing to fabricate bipolar device structures with a minimum feature size of 0.9 /spl mu/m. Both nonisolated I/sup 2/L and isolated Schottky transistor logic (STL) devices and circuits have been fabricated with this process technology. The primary demonstration vehicle is a seated LSI, I/sup 2/L, 4-bit processor chip (SBP0400) with a minimum feature size of 1 /spl mu/m. Scaled SPB0400's have been fabricated that operate at clock speeds 3X higher than their full-size counterparts at 50-mA chip current. Average propagation delay has been measured as a function of minimum feature size for both I/sup 2/L and STL device designs. Power-delay products of 14 fJ for I/sup 2/L and 30 fJ for STL have been measured.     

The low power analogue and digital baseband processing parts of a novel multimode DECT/GSM/DCS1800 terminal

In order to support a multimode DECT/GSM/DCS1800 terminal architecture, with low power characteristics and integrated support for direct conversion terminal architecture, the critical parts of such a terminal were designed and implemented using three different chips. These parts include a baseband processor, a modem and suitable analogue parts. The baseband processor was designed to support multimode operation, all baseband processing required and different terminal architectures (heterodyne or direct conversion). The modem features a GMSK/GFSK modulator and a novel, low power detection algorithm supports a direct conversion terminal. The analogue circuitry includes analogue filters and Digital-to-Analog and Analog-to-Digital converters. The architecture of the direct conversion wireless terminal is presented along with details on the low power characteristics of the processor and the modem. Experimental results from the operation of the multimode terminal are presented.