采用简化自适应混合调制技术的DC-DC转换器

为了在较宽负载范围内获得高的转换效率,采用PWM调制与PSM调制相结合的调制模式,设计了一种混合调制方式DC-DC转换器。设计了一种简单的自适应调制方式切换电路,利用斜坡发生电路的斜坡下降沿,设计了一种新颖的最小占空比信号OSC、VRAMP信号和时钟信号VCLK同步发生电路,简化了电路规模。在轻负载时,采用占空比和输出电压同时检测的方法,将调制模式自动切入PSM调制模式,减小了开关电路工作频率,静态损耗减小了40%。采用65 nm CMOS工艺进行设计。仿真结果表明,该电路在两种调制方式之间可以平稳切换,1 mA负载时工作效率提升到86.3%。     

一种新型的DC-DC芯片设计

本文提出一种可以根据负载变化自动切换等效工作频率的PWM/PFM双模型boostDC-DC电源芯片的电路结构,使得芯片同时具有PFM高效和PWM低纹波的特点。与此同时,采用有效的相位补偿技术解决PWM方式下很可能出现的自激问题。本文在这种结构下并采用流片厂提供的模型参数,对芯片本身及其典型应用电路进行模拟。该芯片可广泛应用于各类便携式电子系统中,更可以作为IP核,嵌入同种工艺下的其它芯片。     

一种基于LMX2485E芯片的调制倍频电路

本文介绍了一种调制倍频单元的设计工作。电路中选用了一种具有跳频功能、可通过编程精确预置带有小数的倍频系数的高分辨率频率合成器芯片,同时实现数字调制、锁相倍频的功能,直接取代原有模拟调制、倍频电路。     

一种基于LMX2485E芯片的调制倍频电路

本文介绍了一种调制倍频单元的设计工作.电路中选用了一种具有跳频功能、可通过编程精确预置带有小数的倍频系数的高分辨率频率合成器芯片,同时实现数字调制、锁相倍频的功能,直接取代原有模拟调制、倍频电路.     

一种高效降压型DC/DC变换器控制电路的设计

设计了一种高效降压型DC/DC变换器控制电路.该电路基于脉冲宽度调制(PWM)方式,电源芯片在开关频率较高的情况下能有效抑制噪声,提高转换效率;采用E/D NMOS电压基准源,输出电压温度特性好,抑制电源噪声能力强,内置软启动电路,抑制输出电压的上冲;补偿网络结构简单,同时也保证了系统的稳定.采用无锡上华CSMC st02 0.5 μm工艺,仿真结果表明,芯片转换效率达到90%以上.     

RFW102无线收发芯片组的原理和应用

RFW102芯片组是一种半双工DSSS(直接序列扩频技术 )的无线收发两用IC ,它采用ASK调制方式 ,工作频率在2.4GHz。文中详细介绍了该芯片组的特点、性能、管脚功能和工作原理 ,给出了RFW102的应用电路     

具扩展频谱频率调制的低EMI DC／DC稳压器电路

本文介绍了一种具有扩展频谱频率调制功能的低EMI的DC/DC负载点开关模式稳压器电路的设计方案,即采用4相并联的μModule系统,实现降低EMI的作用.     

一种电流检测PFM型LED驱动IC的设计

基于开关电源系统基本理论,采用电流检测脉频调制(PFM)模式,设计了一种新型大功率LED照明恒流驱动芯片.利用0.5μm CMOS工艺模型仿真,结果表明,该芯片具有高电源抑制比、2.5～400V宽输入电压范围、10 kHz～2.5 MHz可调工作频率和多种保护功能,LED驱动电流范围为几mA到1A,可驱动1个到几百个LED灯,特别适合大功率恒流驱动.     

基于电流模逻辑的宽频带二分频器设计

设计了一种基于电流模逻辑结构(CML)具有宽频率覆盖范围的二分频器.针对CML电路无法在低频段稳定工作的问题,在传统的CML电路结构中加入了偏置电路,提高了电路的响应速度;并加入了差分结构的电容阵列,在高频段采用较低的输出电容负载,在低频段采用较高的输出电容负载,拓宽了分频器的工作频率范围;同时减少了开关管的使用,有利...     

6A降压DC／DC转换器

NCP6338提供范围为0．6～1．4V、增量为6．25mV的可编程输出电压,同时可采用低至2．3V的输入电压工作。这器件经过了优化,用于为平板电脑和智能手机等便携设备的先进应用处理器供电。NCP6338使用独特的模块化输出强度驱动,加上在脉宽调制（PWM）与脉频调制（PFM）模式之间自动转换的功能,能够根据负载调配其能效性能,因而节省电池电量。     

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.     

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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