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介绍了一种32位对数跳跃加法器结构.该结构采用ELM超前进位加法器代替进位跳跃结构中的组内串行加法器,同ELM相比节约了30%的硬件开销.面向该算法,重点对关键单元进行了晶体管级的电路设计.其中的进位结合结构利用Ling算法,采用支路线或电路结构对伪进位产生逻辑进行优化;求和逻辑的设计利用传输管结构,用一级逻辑门实现"与-民或"功能;1.0μm CMOS工世实现的32位对数跳跃加法器面积为0.62mm2,采用1μm和0.25μm 工世参数的关键路径延迟分别为6ns和0.8ns,在100MHz下功耗分别为23和5.2mW. 相似文献
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对数跳跃加法器的算法及结构设计 总被引:5,自引:0,他引:5
本文介绍一种新型加法器结构——对数跳跃加法器,该结构结合进位跳跃加法器和树形超前进位加法器算法,将跳跃进位分组内的进位链改成二叉树形超前进位结构,组内的路径延迟同操作数长度呈对数关系,因而结合了传统进位跳跃结构面积小、功耗低的特点和ELM树形CLA在速度方面的优势.在结构设计中应用Ling's算法设计进位结合结构,在不增加关键路径延迟的前提下,将初始进位嵌入到进位链.32位对数跳跃加法器的最大扇出为5,关键路径为8级逻辑门延迟,结构规整,易于集成.spectre电路仿真结果表明,在0.25μmCMOS工艺下,32位加法器的关键路径延迟为760ps,100MHz工作频率下功耗为5.2mW. 相似文献
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针对硬件实现BCD码十进制加法需要处理无效码的问题,设计了一种基于并行前缀结构的十进制加法器。该十进制加法器依据预先加6,配合二进制加法求中间和,然后再减6修正的算法,并将减6修正步骤整合到重新设计的减6修正进位选择加法器中,充分利用并行前缀结构大幅提高了电路运算的并行度。采用Verilog HDL对加法器进行实现并利用Design Compiler进行综合,得到设计的32位,64位,128位的十进制加法器的延时分别为0.56 ns,0.61 ns,0.71 ns,面积分别为1 310 μm2,2 681 μm2,5 485 μm2。 相似文献
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本文提出一种规整结构超前进位加法器,其加法时间与位数的对数成比例;而且其结构规整、逻辑简单、互连容易。SPICE模拟表明,采用2μm CMOS工艺的16位加法器最坏情况延时为5.4ns,并具有位数加倍延时仅增加1.2ns的扩展特性。它可以方便地用全定制或半定制等VLSI设计方法实现。 相似文献
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设计一个应用于高性能微处理器的快速64位超前进位对数加法器.通过分析超前进位对数加法器原理,提出了改进四进制Kogge-Stone树算法的64位超前进位对数加法器结构,并结合使用多米诺动态逻辑、时钟延迟多米诺逻辑和传输门逻辑等技术来设计和优化电路.该加法器采用SMIC 0.18 μm CMOS工艺实现,在最坏情况下完成一次加法运算时间为486.1 ps,与相同工艺和相同电路结构采用静态CMOS实现相比,大大减少了加法器各级门的延迟时间,取得良好的电路性能. 相似文献
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通过对计算机加法器的研究,从门电路标准延迟模型出发,在对超前进位加法器逻辑公式研究的基础上,在主要考虑速度的前提下,给出了超前进位加法器的逻辑电路的设计方案。主要对16位、32位加法器的逻辑电路进行分析设计,通过计算加法器的延迟时间来对比超前进位加法器与传统串行进位链加法器,得出超前进位算法在实际电路中使加法器的运算速度达到最优。 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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YUXiao-hua XIANGYu-qun 《半导体技术》2005,30(2):30-32,37
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. 相似文献
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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. 相似文献
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Tian-hua Xu Feng Tang Wen-cai Jing Hong-xia Zhang Da-gong Ji Chang-song Yu Ge Zhou Yi-mo Zhang 《光电子快报》2008,4(4):292-294
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. 相似文献
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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. 相似文献
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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 相似文献
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TANG Bin JIANG Xing-fang LIU Zhi-min 《光电子快报》2008,4(1):78-80
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. 相似文献
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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- 相似文献