宽带低噪声放大器单片微波集成电路

从行波放大器设计理论出发,研制了一款基于低噪声GaAs赝配高电子迁移率晶体管(PHEMT)工艺设计的2~20 GHz单片微波集成电路(MMIC)宽带低噪声放大器。该款放大器由九级电路构成。为了进一步提高放大器的增益,采用了一个共源场效应管和一个共栅场效应管级联的拓扑结构,每级放大器采用自偏压技术实现单电源供电。测试结果表明,本款低噪声放大器在外加+5 V工作电压下,能够在2~20 GHz频率内实现小信号增益大于16 dB,增益平坦度小于±0.5 dB,输出P-1 dB大于14 dBm,噪声系数典型值为2.5 dB,输入和输出回波损耗均小于-15 dB,工作电流仅为63 mA,低噪声放大器芯片面积为3.1 mm×1.3 mm。     

S波段低噪声放大器的ADS仿真与设计

介绍低噪声放大器设计的理论基础,并重点介绍了低噪声放大器的主要性能指标:噪声系数、功率增益、驻波比、稳定性等。以ATF38143晶体管为例介绍了ADS仿真软件设计低噪声放大器的方法和主要步骤。采用三级级联结构设计出满足指标的S波段低噪声放大器链路。该放大器链路的指标为噪声系数小于1.2,功率增益大于50dB,增益平坦度小于0.5dB,VSWR小于1.8的低噪声放大器,带宽为6MHz,并具有一定的带外抑制能力。     

S波段低噪声放大器设计

首先分析了低噪声放大电路的稳定性,功率增益及噪声系数的影响因素及改进方法;然后设计了一个中心频率为2.45 GHz,工作带宽为100MHz的S波段低噪声放大器.仿真结果表明,该放大器的噪声系数小于1 dB,功率增益大于28 dB,增益平坦度小于1 dB,输入/输出驻波比小于2:1.通过传统的电路板制作工艺实际制作了放大器电路,测试结果和仿真结果较一致.     

宽带CMOS低噪声放大器的设计

文章主要介绍应用于集群接收机系统的350MHz～470MHz低噪声放大器,采用0.6μm CMOS工艺。探讨了优化低噪声放大器的噪声系数、增益与线性度的设计方法,同时对宽带输入输出匹配进行了分析。这种宽带低噪声放大器的工作带宽350MHz～470MHz,噪声系数小于3dB,增益为24dB,增益平坦度为±1dB,输入1dB压缩点大于-15dBm。     

S波段小型化宽带低噪声放大器的设计

采用软件计算微带平面电感,描述了一款基于薄膜工艺的小型化宽带低噪声放大器的设计和性能。测试结果表明:在2.7～3.5 GHz的频段内,低噪声放大器的噪声系数小于等于0.55 dB,增益大于等于33 dB,增益平坦度小于等于±0.1 dB;在2～4 GHz的频段内,低噪声放大器的噪声系数小于等于0.65 dB,增益大于等于33 dB,增益平坦度小于等于±0.8 dB;尺寸为6.0 mm×4.2 mm。     

一种S波段平衡式限幅低噪声放大器的设计

介绍了一种小型化平衡式限幅低噪声放大器。该放大器采用Lange桥平衡结构,在实现低噪声的同时,保证了小电压驻波比;在3.0～3.5GHz频带内,噪声系数小于1.3dB,输入输出驻波系数小于1.3,增益大于27dB,平坦度±0.6dB以内,输出1dB压缩点大于12dBm。该放大器能够承受最大5W的连续波功率输入,且大功率输入时的驻波系数小于1.3。     

毫米波高性能收发多功能芯片

利用0.15μm GaAs PHEMT工艺,研制了一款集成功率放大器和低噪声放大器的毫米波多功能单片。发射支路功率放大器采用三级放大拓扑结构,在32~36GHz内,在6V工作电压下,线性增益23dB,增益平坦度优于±0.75dB,输入/输出驻波小于1.3,饱和输出功率30dBm,功率附加效率约30%。接收支路低噪声放大器采用三级放大拓扑结构,在5V、30mA工作电压下,在32~37GHz内,线性增益23.5dB,增益平坦度优于±1dB,噪声系数小于2.5dB,1dB压缩输出功率大于6dBm。该芯片面积为3.67mm×3.13mm。     

2～4GHz MMIC低噪声放大器

采用中国电子科技集团公司第十三研究所的GaAs PHEMT低噪声工艺,设计了一款2~4 GHz微波单片集成电路低噪声放大器(MMIC LNA)。该低噪声放大器采用两级级联的电路结构,第一级折中考虑了低噪声放大器的最佳噪声和最大增益,采用源极串联负反馈和输入匹配电路,实现噪声匹配和输入匹配。第二级采用串联、并联负反馈,提高电路的增益平坦度和稳定性。每一级采用自偏电路设计,实现单电源供电。MMIC芯片测试结果为:工作频率为2~4 GHz,噪声系数小于1.0 dB,增益大于27.5 dB,1 dB压缩点输出功率大于18 dBm,输入、输出回波损耗小于-10 dB,芯片面积为2.2 mm×1.2 mm。     

一种0.03～1.7 GHz超宽带低噪声放大器的设计与制作

为了降低接收机前端的噪声,设计了一种超宽带低噪声放大器。选用噪声较小、增益较高且工作电流较低的放大管,利用负反馈和宽带匹配技术,结合ADS和HFSS微波软件辅助设计,放大器在30 MHz~1700 MHz范围内,增益大于31 dB,平坦度小于±0.5 dB,噪声系数小于2.3 dB,驻波比小于1.6。     

基于反馈技术的宽带低噪声放大器的设计

介绍了宽带放大器的设计方法和负反馈技术。选用增益高、噪声小的高电子迁移率晶体管（HEMT）ATF54143,利用负反馈和宽带匹配技术,设计制作了一个高增益低噪声放大器,并借助于安捷伦公司的微波电路仿真软件ADS进行仿真和优化。测试表明,在50-300 MHz的频率范围内,低噪声放大器的增益大于22 dB,平坦度小于±0.3 dB,噪声系数小于1.25,输入驻波小于1.4,输出驻波小于1.3。     

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.     

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.     

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.     

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.     

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     

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.     

中国建立EB级存储实验室,致力云计算应用(英文)

正With the support of 863 programs,Sugon Information Industry Co.,Ltd.,set up a dawning EB-class storage laboratory to address massive data storage requirements and largescale cloud computing demonstration applications.The Dawning EB-class cloud storage system adopts advanced fault-tolerant architecture,efficient data fault-tolerant algorithms with user authentication and data encryption policies to deal with the"lost""wrong"and"stolen"problems of data for ensuring the reliability and safety of the EB-class storage system in the public network application environments.The Dawning EB-class Storage Laboratory taking advan-