问与答

问：请问ｄＢｉ、ｄＢｄ、ｄＢ、ｄＢｍ、ｄＢｃ之间的区别。 答：它们都是功率增益的单位,不同之处如下。 ｄＢｉ和ｄＢｄ是功率增益的单位,两者都是相对值,但参考基准不一样。ｄＢｉ的参考基准为全方向性天线;ｄＢｄ的参考基准为偶极子。一般认为 ｄＢｉ和 ｄＢｄ表示同一个增益,用ｄＢｉ表示的值比用ｄＢｄ表示的要大２．１５ｄＢｉ。例如：对于一增益为１６ ｄＢｄ的天线,其增益折算成单位为ｄＢｉ时,则为１８．１５ｄＢｉ（一般忽略小数位,为１８ｄＢｉ）。 ｄＢ也是功率增益的单位,表示一个相对值。当计算Ａ的功率相比于 Ｂ…     

宽带毫米波放大器

Ａｌｐｈａ工业公司增加了 5种封装放大器产品 ,以支持微波传感器和通信应用。ＡＢ0 2 8Ｈ1- 14是一种 2 3～ 30ＧＨｚ高增益放大器 ,增益 36ｄＢ ,输出功率 16ｄＢｍ ,噪声系数为 3ｄＢ。ＡＢ0 381- 14的增益为 30ｄＢ ,输出功率 16ｄＢｍ ,噪声系数为 4ｄＢ。二种放大器都为单电源工作。ＡＢ0 2 8Ｖ1- 14是 2 3～ 30ＧＨｚ的可变增益放大器 ,有效增益为 30ｄＢ ,衰减范围为 30ｄＢ ,输出功率 16ｄＢｍ ,噪声系数为 3ｄＢ。二种低噪声放大器ＡＡ0 2 8Ｎ1- 99和ＡＡ0 38Ｎ1- 99工作频率分别为 2 3～ 30ＧＨｚ ,2 6～ 4 2ＧＨｚ。低频型号…     

浅议有线电视中dBmW与dBμV、dBmV之间的换算

有线电视中的ｄＢｍＷ、ｄＢμＶ、ｄＢｍＶ是常用单位 ,《中国有线电视》2 0 0 0年第 2 0期《有线电视系统中的分贝比与电平》一文中已做了比较系统的概述 ,但对于ｄＢｍＷ与ｄＢμＶ、ｄＢｍＶ之间的换算 ,笔者提出不同的意见 ,望与同行共同讨论。先认识一下ｄＢｍＷ、ｄＢｍＶ、ｄＢμＶ的概念。ｄＢｍＷ是以 1ｍＷ为基准功率 ,则功率Ｐ所对应的电平为 10ｌｇ(Ｐ/1ｍＷ) ;ｄＢｍＶ是在有线电视系统中以 1ｍＶ为基准电压 ,则电压Ｕ所对应的电平为 2 0ｌｇ(Ｕ/1ｍＶ) ;ｄＢμＶ是在有线电视系统中以 1μＶ为基准电压 ,则电压Ｕ所对应的电平…     

光纤传输设备的对应数据转换

ＣＡＴＶ领域的光纤设备越来越多 ,必须根据技术要求合理搭配使用光纤设备 ,为此提供以下数据对应表 ,供搭配设备与设计线路时参考。利用表 1可以方便地把电平由一种单位化为另一种单位 ,例如要把 10 5ｄＢμＶ化为ｄＢＷ时 ,可用原来的数与表中最后一行第一列数 - 138.75相加 ,得 - 33.75ｄＢＷ ;如把 10 5ｄＢμＶ化为ｄＢｍ时 ,可用原来的数与表中最后一行第二列 - 10 8.75相加 ,得 - 3.75ｄＢｍ。表 1　电平单位换算表原 单 位增 加 值新 单 位ｄＢＷｄＢｍｄＢｍＶｄＢμＶｄＢＷ 0 +30 +78.75 +138.75ｄＢｍ -30 0 +48.75 +10 8.75ｄ…     

AD604超低噪声双通道可变增益放大器

特点在最大增益情况下具有超低输入噪声０．８０ｎＶ／　Ｈｚ,３．０ｐＡ／　Ｈｚ两个独立通道ｄＢ成线性可变增益放大器每个通道可编程绝对增益范围从０ｄＢ～＋４８ｄＢ（前放增益＝＋１４ｄＢ）到＋６ｄＢ～＋５４ｄＢ（前放增益＝＋２０ｄＢ）增益精度：±１．０ｄＢ－３ｄＢ带宽：４０ＭＨｚ输入电阻：３００ｋ可变增益系数：２０ｄＢ／Ｖ～４０ｄＢ／Ｖ增益对温度和电源变化保持稳定单端单极性增益控制在增益控制低端,电源待机可直接驱动Ａ／Ｄ转换器应用超声和声纳时间增益控制高性能自动增益控制（ＡＧＣ）系统信号测量ＡＤ９８０…     

光纤线路设计调试经验点滴.

在设计光链路时 ,据有关资料介绍往往都要留 1ｄＢ左右的裕量 ,但根据我们实际测试 ,按照这样来设计 ,各光节点的光功率都要偏高。除光发射机输出功率比标称值偏高 0 .8ｄＢ以外 ,光节点处的光功率为 0ｄＢｍ左右 ,而设计值为 - 2ｄＢｍ 1ｄＢｍ ,裕量为 - 1ｄＢｍ ,这样就偏高 1ｄＢ。分析其原因是 :( 1) 1310ｎｍ光纤含熔接损耗在计算时 ,所取的 0 .4ｄＢ/ｋｍ ,比实际的光纤损耗有一定的裕量 ;( 2 )光分路器附加损耗计算时取 0 .55ｄＢ ,而实际为 0 .2 5ｄＢ ;( 3)“光发”、“光收”、光配线架处光纤活动接头计算时按 0 .5ｄＢ/个取值 …     

高隔离度偏振无关光环行器

本文报道了一种高隔离度偏振无关的三端口光环行器。该环行器在１．５５μｍ中心波长±２０ｎｍ范围内，插入损耗低于１ｄＢ，隔离度大于４５ｄＢ，偏振相关损耗低于０．２ｄＢ，串音大于５０ｄＢ，回波损耗大于５０ｄＢ。     

dBASE for Windows中文版

ｄＢＡＳＥｆｏｒＷｉｎｄｏｗｓ中文版童爱华十几年来，ｄＢＡＳＥ深受计算机专家及社会各方面用户的喜爱，现在ｄＢＡＳＥ在全世界已拥有７００多万ＰＣ用户，其ＰＣ数据库市场占有率达５５．８％。Ｂｏｒｌａｎｄ公司１９９５年推出的新一代ｄＢＡＳＥ——ｄＢＡＳＥｆ...     

适合WDM网络动态增益均衡的全光增益锁定光纤放大器

在光纤放大器内部同时建立增益谱锁定与平坦机制，研制出适合ＷＤＭ网络应用的全光锁定高增益、大功率掺铒光纤放大器（ＥＤＦＡ）。在２３ｄＢ输入功率动态范围（－４０～－１７ｄＢｍ）内的增益箝制在３３ｄＢ，对应总输入功率为－１７ｄＢｍ的输出光功率为１６ｄＢｍ，锁定的－１ｄＢ增益带宽为１４ｎｍ（１５４７～１５６１ｎｍ）。     

实用资料

飞利浦CATV放大模块一览表型号(ＭＨｚ)增益(ｄＢ)斜率(ｄＢ)平坦度(ｄＢ)最大值反射损耗 (输入/输出 )(ｄＢ)最小值三阶组合差拍(ｄＢ)最大值交扰调制(ｄＢ)最大值二级组合差拍(ｄＢ)最大值二阶差拍(ｄＢ)最大值输出电平(ｄＢｍＶ)最小值噪声系数(ｄＢ)最大值总ＤＣ电流消耗(ｍＡ)最大值5-75　反向放大器ＢＧＹ68@1 0ＭＨｚ3 0± 0 .8--0 .2～ 0 .5± 0 .2 2 04频道-684频道-60 --702 5ＭＨｚ5.0 1 3 55-1 2 0反向放大器ＢＧＹ66Ｂ@1 0ＭＨｚ2 5± 0 .5--0 .2～ 0 .5± 0 .2 2 01 4频道-661 4频道-54--70 60 .0@1 2 0ＭＨｚ5.0 1 3 55-2 …     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.