一种应用于FPGA时钟管理单元的锁相环设计

设计了一种应用于FPGA时钟管理的可变带宽锁相环.该锁相环采用开关电容滤波器实现可变电阻滤波功能,用反比N电流镜(N为反馈分频系数)来为电荷泵提供偏置,使电荷泵电流与偏置电路电流成1/N的比例关系.本文还提出了用虚拟开关减少了开关两端电压的非理想电荷效应,并设计了一种5级延时单元组成的环形压控振荡器,显著提升了输出频率范围.该锁相环实现了环路带宽与输入频率比值固定,从而使环路带宽能够自动跟随输入频率在较宽范围内变化,保证了其稳定性.本文采用CMOS 65nm数字工艺流片,电源电压为1.2V,作为时钟管理单元IP核嵌入于复旦大学自主研发的FDP5FPGA芯片中.测试表明,本文设计的PLL环路带宽在0.7MHz到13.4MHz能够跟随输入频率在18~252MHz范围内变化,输入频率与环路带宽比值近似为20,产生762MHz~1.7GHz的宽范围输出时钟,阻尼因子均方差不超过8%.     

基于锁相环芯片的锁模激光器稳频方法

提出了一种基于锁相环芯片的方法对作为光源的锁模激光器脉冲重复频率进行锁定,以提高射频拉远系统中光纤链路传输信号的频率稳定度.在分析了由锁相环芯片和锁模激光器构成的锁相环模型的基础上,分别设计和制作了工作于100 MHz和900 MHz的稳频电路,并在实验室环境下对脉冲重复频率约为100 MHz的锁模激光器进行了测试.测试表明,脉冲重复频率的频率稳定度可达到10~(-11),并且工作于900 MHz的稳频电路性能优于100 MHz.可以利用集成度较高的锁相环芯片,简单高效地提高锁模激光器的频率稳定度.     

基于锁相环芯片的锁模激光器稳频方法

提出了一种基于锁相环芯片的方法对作为光源的锁模激光器脉冲重复频率进行锁定,以提高射频拉远系统中光纤链路传输信号的频率稳定度.在分析了由锁相环芯片和锁模激光器构成的锁相环模型的基础上,分别设计和制作了工作于100 MHz和900 MHz的稳频电路,并在实验室环境下对脉冲重复频率约为100 MHz的锁模激光器进行了测试.测试表明,脉冲重复频率的频率稳定度可达到10~(-11),并且工作于900 MHz的稳频电路性能优于100 MHz.可以利用集成度较高的锁相环芯片,简单高效地提高锁模激光器的频率稳定度.     

一种高速低相位噪声锁相环的设计

设计了一种1．8V、SMIC0．18μm工艺的低噪声高速锁相环电路．通过采用环行压控振荡器,节省了芯片面积和成本．通过采用差分对输入形式的延时单元,很好地抑制了电源噪声．与传统的简单差分对反相器延时单元相比,该结构通过采用钳位管和正反馈管,实现了输出节点电位的快速转变,整个电路芯片测试结果表明：在输入参考频率为20MHz、电荷泵电流为40μA、带宽为100kHz时,该锁相环可稳定输出频率为7971MHz—1．272GHz的时钟信号,且在中心频率500kHz频编处相位噪声可减小至-94．3dBc／Hz。     

一种高性能电荷泵锁相环电路的设计与实现

设计了一种电荷泵锁相环电路.采用2/3分频电路、时序鉴相器、差分输入-单端输出结构的电荷泵和多级环形压控振荡器结构,外接PLL环路滤波器,利用SMIC 0.18μm CMOS工艺设计.Hspice仿真测试结果表明,实现的PLL可作为可编程倍频器,可调节范围宽,当锁相环锁住之后,控制电压几乎不变.所设计的PLL满足要求,可应用于频率合成器.     

一个1.2 V用于超宽带收发器的低抖动锁相环

设计了一款应用于超宽带无线收发器中的低抖动、低功耗、多相位输出、输出频率为528MHz和132 MHz的锁相环,包括了高频特性好的鉴频鉴相器、低电压抗抖动的电荷泵、经典的低电压对称负载差分延迟单元以及duty-buffer的双转单电路等.设计采用SMIC 0.13μm CMOS工艺,电源电压1.2 V.对电路进行了电路级仿真和系统级稳定性分析,并完成了版图设计和后仿.根据后仿结果,在TT@75℃、振荡频率为528 MHz情况下,周期抖动的p2p值为1 ps,功耗仅为4 mW.     

电荷泵对小数分频锁相环相位噪声的影响

与整数分频电荷泵锁相环不同,小数分频电荷泵锁相环中电荷泵对锁相环的性能有更大的影响,电荷泵的各种非理想因素将降低PLL输出相位噪声和杂散的性能.重点分析了电荷泵两种非理想因素对小数分频锁相环相位噪声和杂散的影响:非线性和电流失调.此外还分析了电荷泵电流源噪声对小数分频锁相环的影响,分析结果为优化电荷泵的电路设计提供理论依据.     

电荷泵锁相环设计方法研究

在归纳单端输出电流型电荷泵锁相环设计方法的基础上 ,给出单端输出电压型电荷泵锁相环的两种设计方法 :直接近似为电流型输出 ;串接电阻转换为电流型输出 .实验验证了其正确性 ,从而纠正了 Motorola公司设计方法的错误     

锁相环高性能电荷泵电路的设计

设计了一种新型电荷泵电路,该电路采用了差分反相器,可工作在2 V的低电压下,具有速度快、波形平滑、结构简单、功耗低等特点.HSpice仿真结果显示,电荷泵的工作频率为10 MHz时,功耗仅为0.1 mW,输出信号的电压范围宽(0~2 V).该电路可广泛应用于差分低功耗锁相环电路中.     

高性能电荷泵的锁相环电路

为满足锁相环电路高稳定性、低功耗的要求,提高其整体性能,通过对普通型电荷泵锁相环电路模块的改进,设计了一种高性能差分型电荷泵锁相环。该电路包括鉴频鉴相器、分频器、差分电荷泵和压控振荡器的电路结构。仿真结果表明：该差分型电荷泵锁相环的锁定时间为10μs、频率抖动为0.0002MHz、周期抖动为2 ps,与普通型电荷泵锁相环相比,可达到快锁低抖的目的。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.