基于0.18μm CMOS工艺的2.4/5.2GHz双频段LNA的设计

采用0.18 μm CMOS工艺,实现了双频段低噪声放大器设计.通过射频选择开关,电路可以分别工作在无线局域网标准802.11g规定的2.4 GHz和802.11a规定的5.2 GHz频段.该低噪声放大器为共源共栅结构,设计中采用了噪声阻抗和输入阻抗同时匹配的噪声优化技术.电路仿真结果表明:在2.4 GHz频段电路线性增益为15.4 dB,噪声系数为2.3 dB,1 dB压缩点为-12.5 dBm,IIP3为-4.7 dBm;5.2 GHz频段线性增益为12.5 dB,噪声系数为2.9 dB,1 dB压缩点为-11.3 dBm,IIP3为-5.5 dBm.     

5.6GHz CMOS低噪声放大器设计

分析了一种射频COMS共源-共栅低噪声放大器的设计电路,采用TSMC 90nm低功耗工艺实现。仿真结果表明:在5.6GHz工作频率,电压增益约为18.5dB;噪声系数为1.78dB;增益1dB压缩点为-21.72dBm;输入参考三阶交调点为-11.75dBm。在1.2V直流电压下测得的功耗约为25mW。     

应用于无线传感网络的2.4GHz低噪声放大器

采用SMIC0.13μmRFCMOS工艺设计,并实现了应用于无线传感网络的2.4GHz差分低功耗低噪声放大器。在低功耗约束下,电路采用差分共源共栅源极退化电感结构。考虑了ESD保护PAD和封装等寄生电容,分析了输入阻抗匹配、增益、噪声和线性度,提出了低功耗条件下输入阻抗匹配和噪声优化措施。芯片测试结果显示,噪声系数NF为2.5dB,输出采用片外无源网络匹配下功率增益S21为9.4dB,输入三阶交调点IIP3为-1.5dBm。在1.2V电源电压下消耗电流3.3mA。芯片面积为860μm×680μm。     

基于CMOS工艺的一种低功耗高增益低噪声放大器

采用0.18μm CMOS工艺,两级共源结构实现了低功耗高增益的低噪声放大器设计。共源结构的级联采用电流共享技术,从而达到低功耗的目的。电路的输入端采用源极电感负反馈实现50Ω阻抗匹配,同时两级共源电路之间通过串联谐振相级联。该LNA工作在5.2 GHz,1.8 V电源电压,能提供20 dB的增益(S21为20 dB),而噪声系数为1.9 dB,输入匹配较好,S11为-32 dB。     

CMOS低功耗窄带低噪声放大器优化设计

阐述了一个采用Chartered 0.35 μm CMOS工艺实现的应用于315 MHz幅度键控接收芯片的低功耗窄带低噪声放大器.该电路主要采用限定功耗下同时优化噪声性能和输入匹配的技术进行设计,并且采取了其他一些措施来进一步改善电路的性能.采用一个并-串谐振网络,提供镜像抑制.实验测试表明,该低噪声放大器的噪声系数为1.47 dB,功率增益为19.97 dB,输入三阶截断点为-15.53 dBm,镜像抑制为42.4 dB,功耗为1.4 mW.     

基于CMOS工艺的一种低功耗高增益低噪声放大器

采用0．18μm CMOS工艺，两级共源结构实现了低功耗高增益的低噪声放大器（LNA）设计。共源结构的级联采用电流共享技术，从而达到低功耗的目的。电路的输入端采用源极电感负反馈实现50欧姆阻抗匹配。同时两级共源电路之间通过串联谐振相级联。该LNA工作在5．2GHz，1.8V电源电压，能提供20dB的增益（S21为20dB），而噪声系数为1．9dB，输入匹配较好，S11为-32dB。     

低噪声和高增益CMOS下变频混频器设计

设计并实现了一个用于GPS接收机射频前端的CMOS下变频混频器.基于对有源混频器的噪声机制的物理理解,电路中采用了噪声消除技术,以减少Gilbert型混频器中开关管的闪烁噪声,并引入一个额外的电感与开关对共源节点的寄生电容谐振,改善整个电路的噪声系数和转换增益等关键性能指标.电路采用TSMC 0.25 μm RF CMOS工艺实现,SSB噪声系数为7 dB,电压转换增益为10.4 dB,输入1 dB压缩点为-22 dBm,且输入阻抗匹配良好,输入反射系数为-17.8 dB.全差分电路在2.5 V供电电压下的功耗为10 mW,可满足GPS接收机射频前端对低噪声、高增益的要求.     

L波段0.9 mW CMOS LNA的分析与设计

给出了一种采用Γ型输入匹配网络的源简并共源低噪声放大器电路结构,分析了在低功耗情况下,高频寄生效应对低噪声放大器(LNA)输入阻抗及噪声特性的影响,并采用此结构设计了一款工作于L渡段的低功耗低噪声放大器.采用CMOS 0.18μm工艺,设计了完整的ESD保护电路,并进行了QFN封装.测试结果表明.在1.57 GHz工作频率下,该低噪声放大器的输入回波损耗小于-30 dB,输出回波损耗小于-14 dB,增益为15.5 dB,噪声系数(NF)为2.4 dB,输入三阶交调点(IIP3)约为-8 dBm.当工作电压为1.5 V时,功耗仅为0.9 mW.     

应用于2.4GHz无线传感网的低功耗共栅低噪声放大器设计

本文给出一种基于TSMC 0. 18μm RF CMOS工艺、应用于无线传感器网络2.4GHz的低功耗低噪声放大器设计。本设计采用两级级联的交叉耦合共栅结构,第一级共栅级采用电容交叉耦合技术以降低电路功耗的同时提高电路增益、降低电路噪声。第二级共栅级采用正反馈交叉耦合技术以提供一个负阻抵消负载电感的寄生电阻,提高电感等效Q值,进一步提高增益。为了达到足够的增益,作者设计了一款片上差分电感作为负载,对其进行了电磁场仿真,建立了双π模型并进行了流片验证。该低噪声放大器经过流片,测试结果显示：高增益工作情况下,其增益S21为16.8dB,低增益工作情况下为1dB。高增益工作情况下,其噪声系数为3.6dB;低增益工作情况下,电路的输入1dB压缩点为-8dBm,IIP3为2dBm。该低噪声放大器在1.8V电源电压下,工作电流约为1.2mA。     

2.4 GHz CMOS低噪声放大器的设计

设计了一个共源-共源共栅的两级低噪声放大器,并且在两级之间采用了串联谐振回路来提高电路的性能.该电路采用TSMC 0.18μm CMOS工艺,电源电压为1.8 V.仿真结果显示,在2.45 GHz的中心频率上,该电路能够提供26.92 dB的正向增益及很好的输入输出匹配,噪声系数为0.88 dB,功耗为14.49 mW,1dB压缩点为-9dBm.     

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.     

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.     

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.     

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.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

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