高增益自偏S波段MMIC低噪声放大器

报道了具有高增益自偏结构的低噪声S波段MMIC宽带低噪声高增益放大器.该放大器是采用国际先进的0.25μm PHEMT工艺技术加工而成.电路设计采用了两级级联负反馈结构,并采用电阻自偏压技术,单电源供电,使用方便,可靠性高,一致性好.MMIC芯片测试指标如下:在1.9～4.2GHz频率范围内,输入输出驻波小于2.0,线性功率增益达30dB,带内增益平坦度为±0.7dB,噪声系数小于2.7dB.芯片尺寸:1mm×2mm×0.1mm.这是国内报道的增益最高,芯片面积最小的S波段放大器.     

基于RC-CR多相网络的镜频抑制接收机MMIC

基于RC-CR多相网络技术研制了一款S波段镜频抑制接收机单片微波集成电路(MMIC),在MMIC芯片上集成S波段低噪声放大器(LNA)、差分IQ混频器、本振(LO)驱动放大器、RC-CR多相网络滤波器等电路单元,实现了S波段单片镜频抑制接收机,解决了镜频接收机小型化的问题.电路、电磁场软件仿真以及采用GaAs赝配高电子迁移率晶体管(PHEMT)工艺流片后的结果表明,在S波段实现了噪声系数小于1.8 dB,增益大于12 dB,中频(150±5) MHz带内镜频抑制大于35 dBc的技术指标.MMIC的芯片尺寸为4.8 mn×2.5 mm×0.07 mm.此镜频抑制接收机MMIC具有指标优异、体积小、集成度高的特点,可广泛用于各种需小型化的相控阵雷达和通信系统中.     

一款130～140GHz MMIC低噪声放大器

基于90 nm栅长的InP高电子迁移率晶体管(HEMT)工艺,研制了一款工作于130 ～140 GHz的MMIC低噪声放大器(LNA).该款放大器采用三级级联的双电源拓扑结构,第一级电路在确保较低的输入回波损耗的同时优化了放大器的噪声,后两级则采用最大增益的匹配方式,保证了放大器具有良好的增益平坦度和较小的输出回波损耗.在片测试结果表明,在栅、漏极偏置电压分别为-0.25 V和3V的工作条件下,该放大器在130～ 140 GHz工作频带内噪声系数小于6.5 dB,增益为18 dB±1.5 dB,输入电压驻波比小于2:1,输出电压驻波比小于3:1.芯片面积为1.70 mm×1.10 mm.该低噪声放大器有望应用于D波段的收发系统中.     

基于0.15 μm pHEMT的超宽带低噪声放大器

采用RC负反馈、源极电感负反馈等方法,设计并制作了一种基于MMIC技术的3~15 GHz超宽带低噪声放大器,在超宽带范围内实现了优良的回波损耗和平坦的高增益。采用0.15 μm GaAs pHEMT工艺进行设计,该放大器的芯片尺寸为2 mm×1 mm,直流功耗为200 mW。在片测试结果表明,带内增益高达28 dB,4~12 GHz带宽范围内的噪声系数低于2 dB,输入/输出回波损耗大于15 dB,测试结果与仿真结果十分吻合。该低噪声放大器可应用于S,C,X,Ku波段外差接收机以及毫米波、亚毫米波接收机的中频模块。     

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。     

基于QFN封装的X波段GaAs T/R套片设计

基于陶瓷方形扁平无引脚(QFN)封装研制出4款X波段GaAs微波单片集成电路(MMIC),包括GaAs幅相控制多功能芯片(MFC)、功率放大器、低噪声放大器、开关限幅多功能芯片.利用QFN技术将这套芯片封装在一起,组成2 GHz带宽的QFN封装收/发(T/R)组件,输出功率大于1W,封装尺寸为9 mm×9 mm×1 mm.通过提高GaAsMMIC的集成度、放大器单边加电、内部端口匹配,创新性地实现了微波T/R组件的小型化.这几款芯片中最复杂的X波段幅相控制多功能芯片集成了T/R开关、六位数字移相器、五位数字衰减器、增益放大器及串转并驱动器.在工作频段内,收发状态下,增益大于5 dB,1 dB压缩输出功率(P-1)大于7 dBm,移相均方根(RMS)误差小于2.5.,衰减均方根误差小于0.3 dB,回波损耗小于-12 dB,裸片尺寸为4.5 mm×3.0 mm×0.07 mm.     

3.6~4.7GHz低噪声放大器

以一种经典的窄带低噪声放大器结构为基础,分析级联放大器的S参数,通过优化元件参数,获得了一种在3.6~4.7 GH z范围内具有低输入回波损耗、低噪声系数的放大器。采用标准的0.18μm RF CM O S工艺进行了设计和实现。芯片面积为0.6 mm×1.5 mm。测试结果表明:在3.6~4.7 GH z的范围内,该宽带低噪声放大器输入回波损耗小于-14 dB;噪声系数小于2.8 dB,增益大于10 dB。在1.8 V电源下功耗约为45 mW。     

应用于S波段的高线性低噪声放大器

采用E-mode 0.25um GaAs pHEMT工艺,2.0mm × 2.0mm 8-pin双侧引脚扁平封装,设计了一款应用于S波段的噪声系数低于0.5dB的低噪声放大器。通过采用共源共栅结构、有源偏置网络和多重反馈网络等技术改进了电路结构,该放大器具有低噪声,高增益,高线性等特点,是手持终端应用上理想的一款低噪声放大器。测试结果表明在2.3-2.7GHz内,增益大于18dB,输入回波损耗小于-10dB,输出回波损耗小于-16dB,输出三阶交调点大于36dB。     

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。     

基于前馈结构的宽带高线性低噪声放大器

设计制作了一款工作频率范围为0.5~30.0 MHz的短波宽带高线性低噪声放大器。采用前馈法线性化技术实现了放大器的高线性与低噪声,其中主放大器采用平衡式结构线性化技术大幅改善了放大器的二阶失真。由于主放大器和辅助放大器均采用Gain Block MMIC放大器,使得该放大器的物理尺寸为40 mm×25 mm,从而实现了小型化。测试结果表明,该放大器在0.5~30.0 MHz约5.9个倍频程的工作频率范围内实现了增益为12 dB,增益平坦度为0.35 dB,最大噪声系数为3.2 dB,输出三阶截点大于55 dBm,输出二阶截点大于100 dBm。     

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.     

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.     

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.     

Call for Papers

正Communications—VLSI Researches and industries of telecommunications have been growing rapidly in the last 20 years and will keep their high growing pace in the next decade.The involved researches and developments cover mobile communications,highway and last-mile broadband communication,domain specific communications,and emerging D2D M2M communications.Radio communication steps into its