200W平衡式脉冲功率放大器的设计与实现

给出了一种用于发射机末级的大功率脉冲功率放大器的设计方案和测试结果.电路设计采用三级级联、平衡式电路结构以及集总元件和微带线混合匹配网络.在2.3 GHz-2.4 GHz频段,带内增益为47±1.5 dB、脉冲输出功率200 W、回波损耗大于15 dB.测试结果满足给定指标的要求,证明了设计方案的可行性.     

基于平行式液晶技术的可变光衰减器

介绍了一种基于液晶技术的可变光衰减器(VOA)的原理,提出了设计方案,并对器件性能进行了测试.结果表明: 器件可实现小于1 dB的插入损耗,提供0～30 dB的动态衰减范围,小于0.1 dB的分辨率,响应时间小于50 ms.     

一种采用新型复合沟道GaN HEMTs低噪声分布式放大器

设计研制了一种新型的低噪声分布式放大器,采用了栅长为1μm的低噪声复合沟道Al0.3Ga0.7N/Al0.05Ga0.95N/GaN HEMT (CC-HEMT). 给出了低噪声分布式放大器的仿真和测试结果. 测试结果显示低噪声分布式放大器在2~10GHz频率范围内,输入和输出端口驻波比均小于2.0,相关增益大于7.0dB,带内增益波纹小于1dB . 在2~6GHz频率范围内,噪声系数小于5dB;在2~10GHz频率范围内,噪声系数小于6.5dB; 测试结果与仿真结果较吻合.     

光孤子振幅压缩态的产生及检测

利用非对称Sagnac干涉仪得到光孤子振幅压缩态,并利用平衡零差探测系统对其进行测量.本文重点讨论了测量孤子压缩态的光电探测器,给出了设计方案以及测试指标.其中3dB带宽约为10 MHz,饱和功率约为19 mW.利用该探测器测得孤子压缩值约为1.1 dB,考虑系统整体探测效率(75%),可达约1.5 dB.     

Ka波段一体化收发信机设计

Ka波段一体化收发信机是无线通信系统中的重要电路,它对整个系统的噪声系数,灵敏度等关键指标起决定性作用。文中对Ka波段一体化收发信机的工作原理进行了阐述,同时给出了整机功能实现框图,分析了接收通道单元、本振单元、发射通道单元和电源控制单元共4个单元的设计方案,并给出了仿真结果与测试结果。试验结果表明,Ka波段一体化收发信机接收机噪声系数≤2.2 dB、增益≥60 dB、输入输出驻波、相位噪声杂散、镜像抑制等指标均满足技术要求。发射机1 dB压缩点功率≥30 dBm,增益≥50 dB,三阶交调,杂波抑制等均满足实用技术要求,并根据测试结果对Ka波段一体化收发信机的部分技术指标提出了进一步优化的方案。     

2-GHz CMOS射频低噪声放大器的设计与测试

本文采用CMOS工艺,针对无线通信系统前端(Front-end)的低噪声放大器进行了分析、设计、仿真和测试.测试结果表明,该放大器工作在2.04-GHz的中心频率上,3dB带宽约为110MHz,功率增益为22dB,NF小于3.3dB.测试结果与仿真结果能够很好地吻合.     

一种采用新型复合沟道GaN HEMTs低噪声分布式放大器

设计研制了一种新型的低噪声分布式放大器,采用了栅长为1μm的低噪声复合沟道Al0.3Ga0.7N/Al0.05Ga0.95N/GaN HEMT(CC-HEMT).给出了低噪声分布式放大器的仿真和测试结果.测试结果显示低噪声分布式放大器在2～10GHz频率范围内,输入和输出端口驻波比均小于2.0,相关增益大于7.0dB.带内增益波纹小于1d8.在2～6GHz频率范围内,噪声系数小于5dB;在2～10GHz频率范围内,噪声系数小于6.5dB;测试结果与仿真结果较吻合.     

一种新型低成本稳定调制光源的设计与实现

提出了一种新型低成本的光功率可调的稳定调制光源设计方案.该方案通过调节激光器的驱动电流控制调制光源的光功率变化,配以不同的固定衰减器,可以实现调制光源光功率在-40dB～0 dB范围内的连续可调.测试结果表明,该调制光源光功率可以连续可调并且光功率输出稳定.     

一种新型的窄带带通滤波器设计

提出了一种新型的混合结构滤波器形式,通过λ/ 4 和λ/ 2 谐振器来实现窄带滤波器的弱耦合。详细说明了设计原理及过程,并完成了X 波段5 阶切比雪夫窄带带通滤波器的仿真优化、实物制作及性能测试, 测试结果和仿真结果较一致。该滤波器使用介电常数为3.66, 厚度为0.508mm 的Rogers RO4350B 板材, 有着较小的结构尺寸28.17 mm×4.66 mm。仿真结果证实了该滤波器在频率9.80 ~10.23 GHz (3 dB 带宽) 内优异的窄带性能, 在中心频率10 GHz 的相对带宽为4.3%。通带内插入损耗的测试结果小于4.27 dB, 回波损耗则优于-15.05 dB。验证了该形式滤波器设计方案的可行性和优异的窄带性能。     

三波长泵浦实现平坦C L-band光纤拉曼放大

本文介绍了采用三波长泵浦实现C+L- band的拉曼放大器的设计与实现.论文首先给出了理论计算与仿真结果,并在此结果的指导下完成了拉曼放大系统实验系统.测试结果表明,本论文研制的拉曼放大系统可以实现在1 536～1 607 nm,共71 nm带宽范围内的平坦放大,其平均增益为10.5 dB,增益平坦度小于±0.5 dB纹波不超过1 dB.研制的拉曼放大系统的最大有效噪声系数小于一2.96 dB,平均为一3.2 dB.研制的拉曼放大系统同时具有优良的偏振无关特性,测试得出的最大偏振相关增益小于0.4 dB.     

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.     

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.     

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.     

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.     

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.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.