负电荷泵LED驱动芯片的设计与实现

设计了一种负电荷泵低压差电流源白光LED驱动芯片.基于负电荷泵原理,消除了传统正电荷泵结构中电流调整晶体管和地焊盘的寄生电阻,电流调节模块中电流源的压降可以达到80 mV的超低压状态,降低了损耗.采用脉冲信号和使能端设计控制LED驱动电流,可在2.8～5 V工作电压内提供1.25～ 20 mA范围内16个不同的恒定驱动电流,实现LED灯的16级不同亮度的调光功能.电荷泵的输出纹波几乎不会影响LED的亮度与色差.采用CSMC 0.5 μmCMOS工艺完成了芯片的设计.流片测试结果显示,在芯片工作电压范围内,LED电流变化的最大差值为0.4 mA,测试效率达到89.3％,满足高效和稳定的应用要求.     

一种新颖的微处理器电源监控芯片的设计

介绍了一种多功能、低功耗微处理器电源监控芯片的设计方法.此芯片集成了带隙基准电压源、电压比较器、时基振荡、看门狗模块.文中分别对系统中各个模块做了介绍,特别是带隙基准电压源和时基振荡这两个重要模块.其中,带隙基准电压源温度系数只有12 ×10-6,芯片整体功耗电流不超过30 μA.     

用于高能物理实验电子读出芯片的低噪声锁相环芯片设计

基于TSMC 180 nm工艺设计并流片测试了一款用于高能物理实验的电子读出系统的低噪声、低功耗锁相环芯片。该芯片主要由鉴频鉴相器、电荷泵、环路滤波器、压控振荡器和分频器等子模块组成,在锁相环电荷泵模块中,使用共源共栅电流镜结构精准镜像电流以减小电流失配和用运放钳位电压进一步减小相位噪声。测试结果表明,该锁相环芯片在1.8 V电源电压、输入50 MHz参考时钟条件下,可稳定输出200 MHz的差分时钟信号,时钟均方根抖动为2.26 ps(0.45 mUI),相位噪声在1 MHz频偏处为-105.83 dBc/Hz。芯片整体功耗实测为23.4 mW,锁相环核心功耗为2.02 mW。     

一种新型CMOS集成降压源IP模块的设计

目前很多热插拔接口芯片,采用低电压短沟道工艺,从5 V电压得到3.3 V和1.2 V电压的稳压器就成为芯片的一部分.稳压器主要由带隙基准(BGR)、缓冲器、局部电压镜像和全局电流镜像组成.利用Spectre对降压源仿真表明:不带负载功耗280 μA;3.3 V输出偏差在3.5%内,负载电阻下限200 Ω;1.2 V输出偏差在4%以内,负载电阻下限73.5 Ω.该减压源IP模块采用0.13 μm CMOS工艺实现,具有实用性.     

高压、高效率白光LED驱动电路的研究与设计

设计了一种高效率的高输入电压,恒定电流输出的白光LED驱动芯片.采用高压工艺,以脉宽调制(PWM)峰值电流的控制方式,实现了宽范围电压输入、恒定电流输出的LED驱动芯片的设计.内部集成了带隙电压基准源,产生0.25V的参考电压.芯片设计采用了高压横向扩散金属氧化物半导体场效应管(LDDMOS),设计了电压预调整电路,实现了输入电压范围在85V-400V间变化,输出电流在1毫安到1安培间设定.芯片仿真结果显示电能转换效率最高可达90%以上.     

一种基于BCD工艺的汽车电压调节器芯片设计

针对目前车用电压调节器体积大、稳定性差和寿命短等问题,设计了一款用于汽车的电压调节器芯片。该芯片通过PWM技术调整发电机励磁绕组的平均励磁电流,稳定了发电机输出电压。同时,该芯片集成了低温漂、高精度的电压基准源与电流源,还具有欠压锁定与过温保护电路,提高了系统可靠性。芯片基于0.5 μm BCD工艺进行设计,采用Cadence Spectre进行仿真。仿真结果表明,该芯片工作电压是720 V,静态电流仅为472 μA,电压调节范围1020 V,基准电压1.16 V,工作温度范围-40125 ℃,温度系数8.4 ppm·℃ ^-1,且当发电机输出电压波动时,该芯片可使输出电压稳定。     

一种低功耗高动态范围的915MHz无源射频标签

设计了一种适用于NCITS-256-1999协议的915MHz无源射频只读标签.芯片具有低功耗、高动态范围的特点.1.6V电源电压下模拟前端的静态工作电流为1.6μA,芯片正常工作所需要的最小射频信号输入功率为45μW.芯片在0.18μm CMOS工艺下流片验证,测试结果表明,芯片能够很好地满足设计要求.     

一种低功耗高动态范围的915MHz无源射频标签

设计了一种适用于NCITS-256-1999协议的915MHz无源射频只读标签.芯片具有低功耗、高动态范围的特点.1.6V电源电压下模拟前端的静态工作电流为1.6μA,芯片正常工作所需要的最小射频信号输入功率为45μW.芯片在0.18μm CMOS工艺下流片验证,测试结果表明,芯片能够很好地满足设计要求.     

一种14位210MSPS校准电流DAC设计

本文设计了一种3.3V 14位210MSPS电流型DAC。该转换器包括高速模拟开关、带隙参考电路、电流调整电路和高速锁存器等。采用了分段电流沉结构,同时还采取了电流源调整技术,改善了芯片的线性参数。电路基于0.35μm CMOS工艺设计,芯片面积3.8mm2。测试表明,其刷新率可达210MSPS,INL为±0.8LSB,DNL为±0.5LSB,SFDR@fclk=210MSPS为72dBC@fout=5.04MHz,在3.3V电压下工作时功耗小于120mW。本文网络版地址:http://www.eepw.com.cn/article/233873.htm     

高性能电荷泵电路设计与HSPICE仿真

电荷泵锁相环具有高速、低功耗、低抖动等特点.电荷泵是锁相环中的关键模块,它实质上是一个开关电流源,需具有精准稳定的恒流源和理想的开关.在模块运行中,一般会出现电荷共享及充放电电流不匹配等现象.通过自举的方法,可以较好地消除电荷共享现象;采用电流跟随电路,可以使充放电电流得到较好匹配.基于2.5 V 0.25 μm CMOS工艺,设计了一个高性能电荷泵.采用Synopsys公司的Hspice仿真软件,对设计的电路进行模拟仿真.结果显示,在1.45 V至2.0 V之间,充放电电流几乎相等.     

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-