基于有源电容倍增器的新型电荷泵DC-DC变换器

电荷泵中浮置电容是影响输出特性的关键因素,针对大容量浮置电容难以集成的问题,提出利用电流传输器构成有源电容倍增器代替浮置电容的方法,可使等效的浮置电容容量提高1~3个数量级.利用PSPICE软件对反压及倍压电荷泵分别在采用有源电容倍增器和理想电容的情况下进行仿真,对比分析的结果说明采用有源电容倍增器的电荷泵电路仅需要很小的电容就能得到与外加大容量浮置电容电荷泵电路相同的输出特性(实例中100pF可等效50nF),从而基于有源电容倍增器的电荷泵将更易于全单片集成.     

采用有源电容倍增器改善开关电容DC-DC变换器的性能

研究了开关电容DC-DC变换器输出电压与电容的关系,分析了变换器输出电压波纹产生的原因.针对变换器中大电容难集成的问题,提出了一种基于跨导放大器和第二代电流传输器的有源电容倍增器的新型拓扑结构.该电路只用较少的元件就可以实现开关电容变换器中的浮地和接地电容.以二阶开关电容DC-DC变换器为例,用PSPICE软件分别对采用了有源电容倍增器的新型结构和传统结构进行了仿真.结果显示,基于有源电容倍增器的开关电容变换器仅用100pF电容就等效了200nF电容的输出性能,而且具有更低的输出电压波纹.     

互补型复合跟随器构成的模拟电感电路和低耗电容倍增器

本文提出了一种用场效应晶体管和双极型晶体管的互补型复合跟随器构成高Q模拟电感电路和低耗电容倍增器的新方案。这种电感电路和电容倍增器与以往的相比,它们具有电路简单、只用一组电源、温度特性可以互补、适于制作低频段的高感值电感电路和低耗电容倍增器(由于复合跟随器输入阻抗高)等优点。文中分析了这种模拟电感电路和低耗电容倍增器的工作原理;找出了模拟电感电路的Q与(角频率)、Q与r(补偿电阻);电容倍增器的Q与r、(电容倍增系数)与r、Re(损耗电阻)与r的关系;同时还介绍了这种模拟电感电路和电容倍增器的设计方法;并进行了实验验证。最后,导出了这种模拟电感电路的Q值灵敏度的表达式,给出了这种模拟电感电路应用的例子。     

基于可编程跨导运算放大器POTA低通有源滤波器设计

该文给出了基于可编程跨导运算放大器(POTA)的有源滤波器设计方法,能在一定范围内实现跨导值程控调节, 提高调节精度和准确度。并且利用Jacobi法求解相似对角形矩阵,避免解高次方程的难题。所设计的有源滤波电路不易受分布电容的影响,稳定性好、灵敏度低。本文给出了设计实例,显示了该方法的优点。     

陶瓷二次电子倍增器的测试方法及其特性的研究(一)

通道型二次电子倍增器分为玻璃二次电子倍增器和陶瓷二次电子倍增器两个大类,其形式有直管式、弧形、波形、平面螺旋和立体螺旋五种.玻璃二次电子倍增器是用特种高铅玻璃拉成毛细管,在高温(350—400℃)氢气氛中还原,玻璃表面生成一层厚为I00A的N型铅半导体膜所制成的.在国外,这种倍增器于60年代初期出现.有不少文献     

适合集成开关电容DC-DC变换器的浮地电容倍增器

针对在集成电路中制作大容量电容器的困难，提出了一种利用电流传输器提高集成电容器容量的方法，称之为连续可变浮地电容倍增器。分析了电容倍增的机理，建立了相应的关系式，在此基础上对用此浮地电容构成的一阶滤波器和开关电容DC-DC变换器进行了理论分析和PSPICE仿真。结果表明，利用电流传输器的阻抗变换作用，可使小容量的电容等效变换为较大容量的浮地电容，从而便于开关电容DC-DC变换器实现全单片集成。     

电容器

实现高值电容器是集成电路设计中最受限制的问题。本文提出一种新颖的电容倍增器的设计原理,用它可获得更高的电容值。提出并分析了两种解决方法,第一种采用一个带有电流增益的第二代电流传送器(CCⅡ),第二种采用两个 CCⅡ,对 CCⅡ的不理想影响也进行了评估和讨论。最后,报告了一个与理论计算吻合完好的 SPICE 模拟。参14     

高调节范围RF MEMS压控电容的设计与模拟

对传统平行极板MEMS压控电容的局限性进行了理论分析,提出了一种新型的高调节范围MEMS压控电容.它的特点在于使用了三对极板,其中的一对是电容极板,另外两对是控制极板.电容极板用于传输交流信号,而直流控制电压施加在控制极板上.使用有限元分析软件Ansys对其进行了建模与仿真,得出其调节范围高达214%,大大超出了传统的平板电容在调节范围上的自然限制(50%).设计了该电容的工艺流程.其工艺流程比较简单,很容易集成在标准的CMOS集成电路中.     

高调节范围RF MEMS压控电容的设计与模拟

对传统平行极板MEMS压控电容的局限性进行了理论分析,提出了一种新型的高调节范围MEMS压控电容.它的特点在于使用了三对极板,其中的一对是电容极板,另外两对是控制极板.电容极板用于传输交流信号,而直流控制电压施加在控制极板上.使用有限元分析软件Ansys对其进行了建模与仿真,得出其调节范围高达214%,大大超出了传统的平板电容在调节范围上的自然限制(50%).设计了该电容的工艺流程.其工艺流程比较简单,很容易集成在标准的CMOS集成电路中.     

电流模集成电抗元件与频率变换电路的设计

为了拓宽电流模单元电路结构在低压低功耗射频集成电路中的应用,研究把第二代电流传输器用作电抗器件和频率变换电路。以第二代电流传输器为核心,辅助予外围电路,构造从输入到输出端口不同性质传输阻抗的有源电容倍增器和有源电感,并且基于第二代电流传输器组合结构差异的分析,设计了集成频率变换电路。从理论上,推出有源电容倍增器和有源电感结构的合理性。仿真集成频率变换电路,结果袁明对40MHz以下正弦波倍频功能正确,且以100kHz正弦波为调制信号和以10MHz的正弦波为载波获得了双边带调幅信号。这为射频集成电路设计提供了新的思路。     

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-