5位1.5GHz采样频率的Flash ADC的设计及数字后台校正实现

基于TSMC 0.18μm工艺设计了一个单通道5位,1.5GHz Flash模数转换器(ADC),该ADC通过改进跟踪保持电路和采用动态比较器结构实现了数据的高速转换.仿真结果表明,当输入信号达到奈奎斯特频率时,信号与噪声加谐波失真比(SNDR)为24.04dB,无杂散动态范围(SFDR)为29.97dB.为进一步提高此ADC的性能,消除非线性,基于Volterra级数搭建了数字后台校正模型.对比仿真结果,校正后谐波明显下降,SNDR提高了4.91dB,SFDR提高了6.94dB,有效位数提高了约0.82位.     

基于自给时钟的高精度Sigma-Delta ADC设计

为了在电源管理芯片中完成高精度、低功耗的模数转换,提出了1种自给时钟的增量型Sigma-Delta模数转换器(ADC).该ADC由2阶Sigma-Delta调制器结构组成,使用基于过零检测的开关电容积分器代替了基于运算放大器的开关电容积分器,又通过2阶积分器电路的相互触发产生自给时钟,从而无需外部提供时序信号.该ADC使用0.5μm CMOS工艺,在运行500个周期时可以获得的信号噪声失真比(SNDR)为90.06 d B,有效精度为14.66位,转换时间小于330μs,在5 V供电下功耗为0.317 m W.在保持Sigma-Delta ADC较高精度的同时,通过采用基于零点检测的电路减少了所需的外围电路,从而节省了面积.     

10-bit 100-Ms/s视频模拟前端IP核的设计

设计了一个10 bit,100 Ms/s视频模拟前端IP核,并用台积电(TSMC)0.18μm 1.8/3.3 V互补金属氧化物半导体(CMOS)纯数字工艺进行了仿真.电路中模拟部分采用3.3 V电源电压,仿真结果显示当输入信号为18 MHz,信号幅度为满幅(单端1 V,差分2 V)时,输出信号信号-噪声-失真比(SNDR)为60 dB.整个电路的功耗为73 mA,版图面积为2 mm×2.5 mm.     

基于AD7705的高精度极微弱信号A/D转换的电路的设计

在智能仪器仪表设计中,微弱信号转换精度、稳定度的高低直接影响着仪器的性能.为了对极微弱信号进行高精度模数转换,本文设计了以传感器为信号源,仪表放大、低通滤波,运算放大和AD7705芯片为主要结构的转换电路.该电路能够完成对传感器产生的极微弱低频信号进行放大、去噪和模数转换,实验证明本文设计的电路能够有效转换极微弱电信号,为极微弱信号传感器在智能设备中的具体应用提供了合理的解决方案.     

640X512InGaAs探测器低噪声采集系统设计

针对640?512 InGaAs探测器工作原理和输出信号特点,从低噪声角度出发,设计了由探测器驱动电路、信号缓冲电路、单端转差分电路、差分放大电路、模数转换电路、FPGA时序控制电路构成的InGaAs探测器低噪声采集系统。着重解决了在满足驱动的条件下降低系统噪声,对提供精密偏置电压、温控电路和输出信号处理过程给出了详细的设计思想和实现方法。试验结果表明,系统工作正常并获得了良好的噪声特性,整个采集系统暗电平等效均方根(RMS)噪声低于0.3mV。     

640×512 InGaAs探测器低噪声采集系统设计

针对640×512 InGaAs探测器工作原理和输出信号特点,从低噪声角度出发,设计了由探测器驱动电路、信号缓冲电路、单端转差分电路、差分放大电路、模数转换电路、FPGA时序控制电路构成的InGaAs探测器低噪声采集系统。着重解决了在满足驱动的条件下降低系统噪声,对提供精密偏置电压、温控电路和输出信号处理过程给出了详细的设计思想和实现方法。试验结果表明,系统工作正常并获得了良好的噪声特性,整个采集系统暗电平等效均方根(RMS)噪声低于0.3 mV。     

幅度受限系统中基于SNDR的信号功率选择方法

在高斯信道下,幅度受限系统的最佳发送功率选择会直接影响系统性能:信号功率太低会被噪声淹没,功率太高会进入非线性畸变范围,产生信号失真.针对这个问题,通过分析幅度受限系统的信号噪声畸变比(signal to noise-and-distortion rate,SNDR),提出了一种最优信号功率的选择方法.仿真结果表明,采用基于最大SNDR准则的信号功率选择能够获得最好的系统性能.     

基于嵌入式单片机的模数转换精度提高技术及算法

运用嵌入式单片机的内置模数转换(ADC)进行模数转换时,为了提高其转换精度或分辩率,提出了通过多级切换ADC参考电压的方法,研究设计了实现模数转换分辨率成倍提高的处理电路,分析和推导了其实现过程和算法,理论上实现转换精度提高n倍,并以嵌入式单片机PIC18F45K80的内部模数转换模块为操作对象,以提高转换精度到4倍为预期目的﹒实验数据表明:不采用该精度提高技术的模数转换平均误差接近采用该技术的平均误差的4倍,即采用该技术所得转换精度提高达4倍,与预期一致﹒     

低功耗10 bit 40 MS/s流水线型ADC设计

为实现高速低功耗的模数转换,设计了一个工作电压为3.3 V,采样精度为10 bit,采样频率为40 MS/s,流水线结构的模数转换器(ADC).该ADC基于0.35μm互补金属氧化物半导体(CMOS)工艺,通过优化运算跨导放大器(OTA)和低失调动态比较器电流,提高了转换精度,降低了功耗.ADC采用差分输入输出电路,减小了系统噪声的影响.其信噪比为58.3 dB,有效位数为9.4 bit,核心电路面积为1.2 mm×0.8 mm,功耗小于30 mW.     

双通道高速高精度流水线模数转换电路的实现

为解决传统双通道构架仅适用于低速模拟数字转换电路(Analog-to-Digital Converter,简称ADC)的问题,通过取消数字校准电路,去除信号通道中用于数字校准开关的方式,采用台湾积体电路制造公司(TSMC)0.18μm CMOS工艺,用双通道流水线构架实现了高速高精度ADC,确保ADC达到12位信号转换精度的同时,信号转换速度达到了200 Ms/s.通过测试,该电路在模拟输入信号为10 MHz,差分振幅为1.25 V,电源电压为1.8 V,信号采样频率200 Ms/s条件下获得信噪失真比为64.7 d B,无杂散动态范围为86.3 d B,电路整体功耗为356 m W,测试结果证实该设计在降低模数转换电路设计难度的同时节省了功耗.     

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.     

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.     

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。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has