应用于C-X-Ku波段的宽带功率放大器

采用0.25μm AlGaAs/InGaAs/GaAs PHEMT工艺技术,研制出了6～18GHz三级MMIC全匹配宽带功率放大器单片.在6～18GHz的工作频率下,放大器的平均功率增益为19dB,输出功率大于33.3dBm,在10GHz处有最大输出功率34.7dBm,输入回波损耗S11低于-10dB,输出回波损耗S22低于-6dB.与报道的C-X-Ku频段宽带功率放大器相比,有较好的功率平坦度.     

基于InGaP/GaAs HBT的X波段MMIC功率放大器研制

研制了X波段的InGaP/GaAs HBT单级MMIC功率放大器,该电路采用自行开发的GaAs HBT自对准工艺技术制作.电路偏置于AB类,小信号S参数测试在8～8.5GHz范围内,线性增益为8～9dB,输入驻波比小于2,输出驻波比小于3,优化集电极偏置后,线性增益为9～10dB.在8.5GHz进行连续波功率测试,在优化的负载阻抗条件下,P1dB输出功率为29.4dBm,相应增益7.2dB,相应PAE〉40%,电路的饱和输出功率Psat为30dBm.     

基于InGaP/GaAs HBT的X波段MMIC功率放大器研制

研制了X波段的InGaP/GaAs HBT 单级MMIC功率放大器,该电路采用自行开发的GaAs HBT自对准工艺技术制作.电路偏置于AB类,小信号S参数测试在8～8.5GHz范围内,线性增益为8～9dB,输入驻波比小于2,输出驻波比小于3,优化集电极偏置后,线性增益为9～10dB.在8.5GHz进行连续波功率测试,在优化的负载阻抗条件下,P1dB输出功率为29.4dBm,相应增益7.2dB,相应PAE＞40%,电路的饱和输出功率Psat为30dBm.     

下一代移动通信LTE中功率放大器芯片设计

基于0.18μm SiGe BiCMOS工艺,设计了一种应用于下一代移动通信3GPP LTE TDD2.6 GHz频段(Band38)的射频功率放大器(PA)芯片。射频功率放大器采用共发射极3级级联的全差分结构,提高了输出电压摆幅,减小了功率晶体管的集电极电流,且降低了寄生的键合线电感。在预放大级和中间放大级、功率级中分别设计了电阻偏置和有源偏置两种偏置电路以提高线性度性能,并通过MOS开关管实现功率控制功能。测试结果表明:在2.57～2.62 GHz工作频段内,正向增益S21大于30.5 dB,输入回波损耗S11和输出回波损耗S22分别均小于-13 dB,功率增益大于31 dB,输出1 dB压缩点功率达28.6 dBm,功率附加效率为18%。     

一种W波段高输出功率放大器模块

提出了基于GaAs 微波单片集成(MMIC)的W波段高输出功率放大器模块。该模块包括MMIC功率放大器(PA)和波导-微带转换结构。采用功率合成技术和微带耦合电容,实现了低损耗匹配网络,提高了PA的增益和输出功率。采用阶梯匹配网络,拓宽了微带转换过渡的带宽。测试结果表明,在75~105 GHz频率范围内,波导-微带转换结构的插入损耗为0.9~1.7 dB,回波损耗小于11 dB; 在90 GHz频率时,PA的增益S21大于10 dB, 输入/输出反射系数S11/S22小于-10 dB,饱和输出功率为19 dBm。     

GaN MMIC六位数字衰减器的设计

基于GaN HEMT工艺成功研制出一款宽带六位数字衰减器,衰减范围为0～31.5 dB.通过研究GaN HEMT开关器件模型及电阻式衰减网络,选取合适的衰减器拓扑,减小了衰减器的插入损耗,提高了衰减精度,缩小了芯片尺寸.测试结果表明,在2～ 18 GHz频带内,该衰减器的插入损耗小于4.8 dB,64态衰减精度均方根误差小于0.6 dB,输入回波损耗小于-13 dB,输出回波损耗小于-12.5 dB,附加相移为-14°～4°.在10 GHz下,其1 dB压缩点输入功率达到34.5 dBm.裸片尺寸为2.30 mm× 1.10 mm.     

基于GaN HEMT的155～172 GHz功率放大器设计

设计了一款G波段GaN HEMT功率放大器。放大器采用级联结构,在每级设计中均引入了并联反馈。放大器工作频段内的小信号增益大于25 dB,3 dB带宽为17 GHz。大信号测试结果显示,在155～172 GHz饱和输出功率为14～17 dBm;在165 GHz饱和输出功率密度为17 dBm,对应的功率密度为1.25 W/mm。该功率放大器直流损耗功率为1 060 mW,峰值功率附加效率为4.7%。     

X波段GaN MMIC低噪声放大器设计

采用SiC衬底0.25 μm AlGaN/GaN高电子迁移率晶体管(HEMT)工艺,研制了一款X波段GaN单片微波集成电路(MMIC)低噪声放大器(LNA).放大器采用三级级联拓扑,第一级采用源极电感匹配,在确保良好的输入回波损耗的同时优化放大器噪声系数;第三级采用电阻电容串联负反馈匹配,在尽量降低噪声系数的前提下,保证良好的增益平坦度、输出端口回波损耗以及输出功率.在片测试表明,在10 V漏级电压、-2 V栅极电压偏置下,放大器静态电流为60 mA,8～12 GHz内增益为22.5 dB,增益平坦度为±1.2 dB,输入输出回波损耗均优于-11 dB,噪声系数小于1.55 dB,1 dB增益压缩点输出功率大于11.9 dBm,其芯片尺寸为2.2 mm×1.1 mm.装配测试表明,噪声系数典型值小于1.6 dB,可承受33 dBm连续波输入功率.该X波段GaN低噪声放大器与高功率放大器工艺兼容,可以实现多功能集成,具有广阔的工程应用前景.     

X波段宽带单片低噪声放大器

从获取放大器的等噪声系数圆最大半径的角度来进行电路设计,设计了工作于X波段9～14GHz的宽带低噪声单片放大器,采用法国OMMIC公司的0.2μmGaAsPHEMT工艺(fT=60GHz)研制了芯片。在片测试结果为在9～14GHz,噪声系数<2.5dB,最小噪声系数在10.4GHz为2.0dB,功率增益在所需频段9～14GHz大于21dB,输入回波损耗<-10dB,输出回波损耗<-6dB。在11.5GHz,输出1dB压缩点功率为19dBm。     

Ka频段PHEMT 1W功率单片放大器

设计制作了Ka频段高输出功率的单片功率放大器.基于河北半导体研究所的0.25μm栅长的75mm GaAsPHEMT工艺制作的三级功率放大器,芯片尺寸为19.25mm2(3.5mm×5.5mm).在32.5～35.5GHz的频率范围内,小信号线性增益大于16dB,带内平均1dB增益压缩点输出功率为29.8dBm,最大饱和输出功率为31dBm.     

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.     

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.     

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.