一种宽温度范围低温度系数的CMOS带隙基准电路

为得到适用于温度传感器、AD/DA和LDO等精密系统的高精度基准电压,提出基于高阶非线性补偿的5段分段补偿技术,在-40～125℃的宽温度范围内,实现一种高精度带隙基准(BGR)电路. 5段分段补偿技术基于电流镜组合构成的电流加减电路实现. BGR电路基于3.3 V电源供电的0.18μm CMOS工艺完成设计.仿真结果表明,所设计BGR电路的温度系数(TC)为0.05×10~(-6)/℃,工作电流约为28μA,电源抑制比(PSRR)约为-100 dB@dc,线性调整率约为11.8μV/V.     

一种用于用户线接口电路的输出电流放大器

提出了一种输出电流放大器电路。该电流放大器是用户线接口电路 ( SLIC)的关键部分 ,它由运算放大器和精密匹配的电阻组成 ,能较好地实现馈电和语音信号传输功能 ,易于 SL IC实现极性反转和用户线交流阻抗调整。运算放大器由两级组成 ,并进行了 HSPICE电路模拟验证。芯片用 90 V高压双极工艺制造 ,面积约为 2 mm2 ,其工作电压为 5V和 - 48V。经测试 ,馈电电压从 - 35V到 - 52 V,芯片都能正常工作 ,其馈电电流可达± 2 4 m A,语音信号传输性满足国内外标准 ,能满足 SL IC的应用     

用于流水线ADC的无采样保持运放前端电路

为了降低流水线模数转换器功耗与提升输入信号范围，设计了一种无采样保持运放前端电路. 移除采样保持运放降低了功耗，并改进开关时序进一步降低电路功耗；同时改进传统开关电容比较器输入，使得模数转换器可达到0 ~ 3.3 V满电源电压的量化范围. 将设计的无采样保持运放前端电路应用在一款低功耗12位50 MS/s流水线模数转换器进行验证，采用0.18 μm 1P6M工艺进行流片，芯片面积为1.95 mm2. 测试结果表明：3.3 V电压下，采样率为50 MS/s、输入信号频率为5.03 MHz时，信噪失真比（SNDR）为64.67 dB，无杂散动态范围（SFDR）为72.9 dB，功耗为65 mW.     

一种输出可调的高性能带隙基准源设计

设计了一款用于直流电源变换器(regulator)的高性能带隙基准电路,电路结构简洁新颖,并具有输出参考电压可调的优点.Spectre仿真表明,在输入电压为3.3 V±0.3 V,输出约为288 mV的典型应用中,当温度从-40℃～125℃变化时温度系数低至2.13×10-6(ppm)K(TT工艺角下),低频时电源抑制比可达78 db.     

基于硅带隙能量的1.2V基准电压源设计

基于0.35μm CSMC(central semiconductor manufacturing corporation)工艺设计,并流片了一款典型的带隙基准电压源芯片,可输出不随温度变化的高精度基准电压。电路包括核心电路、运算放大器和启动电路。芯片在3.3V供电电压,-40~80℃的温度范围内进行测试,结果显示输出电压波动范围为1.212 8~1.217 5V,温度系数为3.22×10-5/℃。电路的版图面积为135μm×236μm,芯片大小为1mm×1mm。     

一种低噪声交叉耦合结构集成石英晶体振荡器

通过改进电路结构,采用CMOS交叉耦合结构提供负阻,设计一种20 MHz的集成石英晶体振荡器.在该振荡器中,采用共模反馈使其输出稳定的直流电平,并增加RC高通滤波器和预抑制电路降低其相位噪声.基于NUVOTON 0.35μm CMOS工艺,利用Cadence Spectre对电路进行仿真,结果表明,在电源电压为3.3V,偏置电流约400μA时,该振荡器的起振时间约为1.5ms,输出波形峰-峰值为1.08V,输出直流电平约为801.6mV.输出信号频率为19.95 MHz,相位噪声分别可以达到-155dBc/Hz@1kHz,-164dBc/Hz@10kHz.     

高频电流模四象限CMOS模拟乘法器

本文提出了一种新型四象限CMOS模拟乘法器,其核心组成为工作于三极管区的NMOS晶体管和高频CCII(第二代电流传输器)电路.基于2μmP阱CMOS工艺参数的模拟结果显示,当电源电压为±5V,在±4V的输入范围内,其非线性误差小于2.8‰,运算误差小于3.3‰.X输入端的-3dB带宽为22MHz,Y输入端的-3dB带宽为82MHz.     

一种4 M-Pixel/s 4通道X射线CCD读出电路

本文设计了一种4 M-pixel/s 4通道X射线CCD读出电路.为加快读出速度,采用相同的4个通道并行处理CCD信号,每通道由2个3阶3位增量型ΣΔ模数转换器(I-ΣΔADC)交替采样CCD信号进行量化.在调制器结构中引入环路延时迁移(SLD)缓解紧张的时序.设计实例采用0.35μm 2P4M CMOS工艺实现,芯片工作在3.3V电源电压和64MHz时钟频率下,设计获得前端电路折算到输入的等效积分噪声为13.53μV,积分非线性为0.009 6%,功耗为1.35W.     

一种用于SKA的SiGe宽带低噪声放大器

文章设计了一款用于平方公里阵列(Square Kilometer Array,SKA)接收前端的异质结双极型晶体管(heterojunction bipolar transistor,HBT)低噪声放大器。放大器的第1级在反馈电感的基础上采用电容负载,利用晶体管寄生电容拓展带宽;第2级利用发射极跟随放大器实现宽带内稳定的输出阻抗。采用HHNEC 180 nm SiGe工艺对电路进行仿真,版图仿真结果表明,在0.5～1.5 GHz内,噪声系数低于1.16 dB,最小噪声系数为0.76 dB,S_(21)大于15 dB。整个电路尺寸为1.1 mm×0.98 mm(含焊盘),在3.3 V供电电压下,功耗为34 mW。     

一种适用于数模转换电路的带隙基准电压源

文章设计了一种应用于D/A转换器芯片中的带隙基准电压电路,在3 V工作电压下具有极低的温度系数,输出电压低于传统带隙基准电路.该电路改进了传统带隙基准电路,减小了运放失调和电路误差,通过电阻二次分压降低了基准输出电压.在SMIC 0.35 μm CMOS工艺下,使用Hspice进行了仿真.仿真结果表明:该基准的温度系数在-40～100 ℃的范围内仅为3.6×10-6 /℃;电源电压在2.7～3.3 V之间变化时,电源抑制比为52 dB.该文设计的带隙基准电压源完全符合设计要求,是一个性能良好的基准电路.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

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.     

A computer generator for randomly layered structures

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

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to