一种采用有源电感的可调增益小面积超宽带低噪声放大器

设计了一款采用可调谐有源电感（TAI）的可调增益的小面积超宽带低噪声放大器(LNA),输入级采用共基极结构,输出级采用射随器结构,分别实现了宽带输入和输出匹配;放大级采用带有反馈电阻的共射共基结构以取得宽的带宽,并采用TAI作负载,通过调节TAI的多个外部偏压使LNA的增益可调。结果表明,该LNA在2~9GHz的频带内,通过组合调节有源电感调节端口的偏压可实现S21在16.5~21.1dB的连续可调;S11小于-14.7dB;S22小于-19.3dB;NF小于4.9dB;芯片面积仅为0.049mm2。     

一种利用衰减器实现的超宽带可变增益放大器

提出了一种基于有源可调衰减器的超宽带可变增益放大器,以有源可调衰减器作为可变增益放大器的核心,并与高增益放大器级联,在3.1～10.6 GHz超宽频带内实现了宽动态增益调节范围.基于Jazz 0.35 μm SiGe HBT工艺,完成了超宽带可变增益放大器的设计,利用安捷伦公司的ADS仿真软件进行仿真验证.结果表明,在3.1～10.6 GHz的超宽频带内,当电压在0.7～2.0V的范围内变化时,该放大器的动态增益变化范围大于60 dB,3dB带宽大于7 GHz,在整个电压变化范围内,S11和S22均低于-10 dB,在最大增益处,噪声系数小于5dB.     

一种多模多频无线收发器前端SiGe BiCMOS低噪声放大器

基于IBM 0.18μm SiGe BiCMOS工艺,提出了一种应用于2.4～2.5GHz 802.11b/g频段的低噪声放大器(LNA).电路采用全差分发射极电感负反馈共射共基(Cascode)结构,对称电感有效地降低了芯片面积,优化了电路性能.仿真结果表明:该电路在2.4 GHz到2.5 GHz频率范围内,增益(S21)达到25 dB,噪声系数(NF)小于1.5 dB,大幅度提高了收发机系统的性能.此外,输入和输出匹配(S11,S22)分别达到-15 dB,1 dB压缩点大于-25 dBm.电源电压为2.5 V时电路总电流为3 mA.     

应用于SC-UWB收发机的CMOS射频接收前端电路设计

设计了应用于单载波超宽带（SC-UWB）无线收发机中的CMOS射频接收前端电路. 该前端电路采用直接变频结构,包含一个差分低噪声放大器（LNA）、一个正交混频器和两个中频放大器。其中,LNA采用源级电感负反馈结构.首先给出了该类型LNA中输入匹配带宽关于栅源电容、工作频率及匹配目标值的表达式 然后考虑到栅极片上电感、键合电感及其精度,提出了在增益和功耗约束下的噪声因子优化策略。该LNA利用两级放大级的不同谐振点实现了7.1~8.1GHz频段上的平坦增益,并具有两种增益模式来改善接收机动态范围. 正交混频器采用折叠式双平衡吉尔伯特结构. 该射频前端电路采用TSMC0.18um RF CMOS工艺设计,芯片面积为1.43 mm2. 在高、低增益模式下,测得的最大转换增益分别为42dB和22dB,输入1dB压缩点为-40dBm和-20dBm,S11低于-18dB和-14.5dB,中频3dB带宽大于500MHz. 高增益模式下双边带噪声因子为4.7dB. 整个电路在1.8V供电电压下功耗为65mW。     

3～5 GHz超宽带无电感CMOS低噪声放大器设计

基于TSMC O.18μm RFCMOS工艺设计了一种无电感并联负反馈的超宽带低噪声放大器(LNA).在3～5 GHz工作频率范围内,电阻电流复用技术为整体电路提供自偏置,使其在足够的带宽范围内均可实现较高增益;同时噪声相消技术又可消除部分沟道热噪声,在很大程度上降低了放大器的噪声系数,由仿真结果可以看到:LNA在3～5 GHz内实现了良好输入输出匹配和较好的线性度,同时得到了较好的电压增益和噪声性能;并且其在整个频带范围内增益达到11～13.9 dB,噪声系数小于4.6 dB.整个设计最大的优点是没有用到片上电感,使得芯片面积大大缩小,这对商业应用具有极大的吸引力。     

单片集成CMOS光接收前端电路设计

文中采用SMIC 0.18μm CMOS工艺设计了适用于芯片间光互连的的接收机前端放大电路,将跨阻放大器(TIA)和限幅放大器(LA)集成于同一块芯片中.跨阻放大器采用调制型共源共栅(RGC)结构来提高其带宽,限幅放大器采用二阶有源反馈结构和有源电感负载来获得高的增益带宽积.整个接收机前端放大电路具有85dB中频增益,-3dB带宽为4.36GHz.芯片的面积为1mm×0.7mm,在1.8V电源电压下功耗为144mW.     

一种低功耗K频段低噪声放大器

基于0.13μm锗硅(SiGe)双极型互补金属氧化物(Bipolar Complementary Metal Oxide Semi-conductor,BiCMOS)工艺,设计制作了一种高增益低功耗K频段低噪声放大器(Low Noise Amplifier,LNA),通过优化晶体管尺寸及利用硅通孔设计高品质因数射极退化电感,降低了LNA噪声.实测结果表明,在1.6 V偏置条件下,该LNA在20 GHz的噪声系数等于1.94 dB,输入1 dB压缩点等于-29.6 dBm;18～21.3 GHz频率范围内,LNA增益大于23.3 dB,S11和S22均小于-10 dB.包含偏置电路功耗在内,芯片功耗仅21 mW,优于其他同等噪声系数的K频段SiGe BiCMOS LNA.该LNA可应用于卫星通信等K频段低功耗接收机系统.     

低功耗CMOS射频低噪声放大器的设计

介绍了一个针对无线通讯应用的2.1 GHz低噪声放大器(LNA)的设计.该电路采用Chartered 0.25 μm CMOS工艺,电源电压为2.5 V,设计中使用了多个电感,详述了设计过程并给出了优化仿真结果. 模拟结果显示,该电路能提供21.63 dB的正向增益(S21),功耗为12.5 mW,噪声系数为2.1 dB,1 dB压缩点为-19.054 1 dBm.芯片面积为0.8 mm×0.6 mm.测试结果达到了设计指标,一致性良好.     

基于0.18μm CMOS工艺的3.1~10.6GHz超宽带LNA设计

本文基于特许0.18μm CMOS工艺,提出了一种新型的低复杂3.1~10.6GHz超宽带LNA电路,它由两级简单的放大器通过级间电感连接构成。第一级放大器使用电阻电流复用结构和双电感退化技术来达到宽带输入匹配和低噪声性能,第二级放大器使用带电感峰值技术的共源级放大器来同时达到高平坦增益和好的宽带性能。测试结果表明,在3.1~10.6GHz频段内,提出的超宽带LNA的最大功率增益为15.6dB,S12为-45dB,输入输出隔离度小于-10dB,噪声系数NF为2.8~4.7dB,在6GHz时的输入三阶交调点IIP3为-7.1dBm。芯片在1.5V电源电压下,消耗的功率为14.1mW,芯片总面积为0.8mm0.9mm。     

1.8～2.7GHz可调谐八波段时分LTE多模接收机前端的分析与设计

摘要：本文阐述了支持八波段可调谐时分LTE多模接收机前端的分析与设计,覆盖1.8～2.7GHz频率范围并支持5/10/15/20MHz三种带宽和QPSK/16QAM/64QAM 三种调制方式。零中频可调谐接收机前端的设计包括了可调谐窄带可变增益低噪声放大器,电流型下变频混频器和二阶低通输出跨阻放大器,可变增益预放大器,可调谐四阶切比雪夫低通信道选择滤波器和截止频率矫正电路,中频可变增益放大器。 窄带低噪声放大器可以在调谐范围内自由调节中心频率,从而替代了传统多模接收机中的低噪声放大器阵列,节省了芯片面积。模拟基带部分也可以通过数字接口调节增益和信道选择带宽。芯片在SMIC 0.13μm 1P8M CMOS上实现,测试结果显示双边带噪声系数达到4.6dB, 带外IIP3达到-14.5dBm,30～94dB增益范围。1.2V电源电压下芯片消耗功耗为54mA。     

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.