一种新型的5GHz自适应偏置及可变增益低噪声放大器

该文提出了一种新型的自适应偏置及可变增益低噪声放大器(LNA),利用电荷泵(亦称电压倍增器)将LNA输出信号转换成与LNA射频输入信号功率成比例变化的直流信号,以此信号同时反馈控制LNA的偏置和增益,来实现自适应偏置以及可变增益低噪声放大器, 从而极大地改善了LNA的输入线性范围。鉴于5GHz频率下,Bipolar相对于CMOS更好的频率特性和低噪声特性,该项研究采用了BiCMOS工艺,实现了低于3.0dB的噪声系数(高增益状态下)和大约13dBm的输入三阶交调点IIP3的控制范围以及大于15dB的增益控制范围。     

基于Cascode级间匹配的多频段LNA设计

提出了一种Cascode级间匹配电路,能够优化Cascode放大器的噪声系数、增益及高频稳定性。应用该电路,设计了一款多频段射频低噪声放大器(LNA)。采用0.25μm GaAs工艺进行实现,输入、输出阻抗匹配网络采用片外元件。测试结果表明,通过重配置片外元件的参数,该LNA可工作于0.7~1.1 GHz、1.6~2.1 GHz、2.3~2.8 GHz这三个频段,增益分别为25±2 dB、19.5±0.5 dB和18±1 dB,噪声系数分别低于0.6 dB、0.7 dB和0.9 dB,OIP3均大于30 dBm。该LNA对于GSM/WCDMA/LTE通信基站以及L/S频段接收机等设备具有一定的应用价值。     

1MHz～40GHz超宽带分布式低噪声放大器设计

为满足宽带系统中低噪声放大器(LNA)宽带的要求,采用0.15μm GaAs赝配高电子迁移率晶体管(PHEMT)工艺,设计了两款1 MHz^40 GHz的超宽带LNA,分别采用均匀分布式放大器结构及渐变分布式放大器结构,电路面积分别为1.8 mm×0.85 mm和1.8 mm×0.8 mm。电磁场仿真结果表明,1 MHz^40 GHz频率范围内,均匀分布式LNA增益为15.3 dB,增益平坦度为2 dB,噪声系数小于5.1 dB;渐变分布式LNA增益为14.16 dB,增益平坦度为1.74 dB,噪声系数小于3.9 dB。渐变分布式LNA较均匀分布式LNA,显著地改善了增益平坦度、噪声性能和群延时特性。     

一种具有新型增益控制技术的CMOS宽带可变增益LNA

高速超宽带无线通信的多标准融合是未来射频器件的发展趋势,该文提出一种基于CMOS工艺、具有新型增益控制技术的宽带低噪声放大器(LNA),采用并联电阻反馈实现宽带输入匹配,并引入噪声消除技术来减小噪声以提高低噪声性能;输出带有新型6位数字可编程增益控制电路以实现可变增益。采用中芯国际0.13m RF CMOS工艺流片,芯片面积为0.76 mm2。测试结果表明LNA工作频段为1.1-1.8 GHz,最大增益为21.8 dB、最小增益8.2 dB,共7种增益模式。最小噪声系数为2.7 dB,典型的IIP3为-7 dBm。     

一种采用双耦合等效跨导增强技术的94GHz CMOS LNA

采用55 nm CMOS工艺,设计了一款应用于毫米波成像系统的94 GHz低噪声放大器(LNA)。提出一种双耦合等效跨导增强技术,在提高增益的同时,实现良好的宽带输入匹配。使用中和电容技术和共栅管栅端短接技术,进一步提高增益,并保证放大器的高频稳定性。芯片测试结果表明,LNA的小信号增益最大值达到14.2 dB,3 dB带宽为87.1～95 GHz,噪声系数为6.7dB,输入1 dB压缩点为-13dBm。     

基于遗传算法的微波低噪声放大器的优化与实现

微波低噪声放大器(LNA)是微波通信系统中接收机的重要器件,其性能直接影响了通信质量的好坏.采用遗传算法这一全局搜索性能较好的数值算法对LNA的增益及噪声进行了优化,根据优化算法设计了2 GHz的微波低噪声放大器,给出了优化设计步骤及实际电路,并对器件进行了测试,可以看出改进后的器件增益增加了3.4 dB,噪声系数降低了0.5,达到了满意的效果.     

一种130~150 GHz毫米波低噪声放大器

基于65 nm CMOS工艺,设计了一种工作于130~150 GHz的毫米波低噪声放大器(LNA),它采用五级级联共源组态的拓扑结构。第一级电路采用最小噪声匹配,保证了放大器的噪声性能。后级电路采用最大增益匹配,保证电路具有较高的增益。对无源器件进行了结构优化,电感的品质因数在140 GHz处达到15以上。仿真结果表明,在1.2 V电源电压、0.45 V栅极偏置电压下,该LNA的直流功耗为54.1 mW。在130~150 GHz频带内,噪声系数小于7.5 dB,增益大于18 dB。芯片尺寸为0.5 mm×0.3 mm。该LNA有望被应用于D波段接收系统中。     

SiGe HBT低噪声放大器的设计与制造

该文设计和制作了一款单片集成硅锗异质结双极晶体管(SiGe HBT)低噪声放大器(LNA)。由于放大器采用复合型电阻负反馈结构,所以可灵活调整不同反馈电阻,同时获得合适的偏置、良好的端口匹配和低的噪声系数。基于0.35 m Si CMOS平面工艺制定了放大器单芯片集成的工艺流程。为了进一步降低放大器的噪声系数,在制作放大器中SiGe器件时,采用钛硅合金(TiSi2)来减小晶体管基极电阻。由于没有使用占片面积大的螺旋电感,最终研制出的SiGe HBT LNA芯片面积仅为0.282 mm2。测试结果表明,在工作频带0.2-1.2 GHz内,LNA噪声系数低至2.5 dB,增益高达26.7 dB,输入输出端口反射系数分别小于-7.4 dB和-10 dB。     

基于混合集成的高增益光接收模块北大核心

针对光载无线通信(RoF)系统对高增益、小型化光接收模块(ROSA)的需求,基于混合集成技术,设计并制作了一种高增益的四通道ROSA器件,尺寸为20.0 mm×14.0 mm×5.9 mm。模块内集成了低噪声放大器(LNA)芯片以提高射频信号增益,建立了射频信号传输电路,并对器件特性进行了仿真分析。经测试,器件的射频信号增益达14 dB,-3 dB带宽为23 GHz,在1550 nm波长的入射光下,器件的响应度为0.81 A/W,相邻信道之间的射频信号串扰小于-40 dB。该模块对于减小RoF系统的体积和功耗具有重要意义。     

2～18 GHz GaAs超宽带低噪声放大器MMIC

基于90 nm GaAs赝配高电子迁移率晶体管(PHEMT)工艺设计并制备了一款2～18 GHz的超宽带低噪声放大器(LNA)单片微波集成电路(MMIC)。该款放大器具有两级共源共栅级联结构，通过负反馈实现了超宽带内的增益平坦设计。在共栅晶体管的栅极增加接地电容，提高了放大器的高频输出阻抗，进而拓宽了带宽，提高了高频增益，并降低了噪声。在片测试结果表明，在5 V单电源电压下，在2～18 GHz内该低噪声放大器小信号增益约为26.5 dB,增益平坦度小于±1 dB,1 dB压缩点输出功率大于13.5 dBm,噪声系数小于1.5 dB,输入、输出回波损耗均小于-10 dB,工作电流为100 mA,芯片面积为2 mm×1 mm。该超宽带低噪声放大器可应用于雷达接收机系统中，有利于接收机带宽、噪声系数和体积等的优化。     

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.     

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.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.