用一种新的补偿方法实现低压差线性稳压器

使用一种新的频率补偿方法设计了一种100 mA低压降CMOS线性稳压器(LDO).所设计的LDO仅使用了一个PMOS管进行补偿,无需使用电路内部其他的补偿电容和补偿电路就能保持稳定.使用0.18 μm工艺仿真结果表明,设计的LDO使用4.7 μF的负载电容,具有高的PSRR和很好的瞬态反应特性,在负载电流从0 mA跳变到100 mA以及从100 mA跳变到0 mA的时候,输出的变化小于8 mV,反应时间小于1μs,且在1kHz的时候PSRR为-72.3 dB.     

高PSRR超低噪声的LDO设计

便携式医疗电子设备在信号传输中易受到噪声干扰,为了抑制交流纹波对微小信号的影响,设计了一种高电源抑制比(power supply rejection ratio, PSRR)、超低噪声的低压差线性稳压器(low-dropout regulator, LDO)。利用电流缓冲和动态零极点追踪补偿技术来实现环路的稳定,同时也扩展了环路的单位增益带宽,提高了高频下的PSRR。稳压器采用两级结构,通过预稳压调制级加低通滤波器结构来实现低压差线性稳压器的超低噪声,且低通滤波器的截止频率有利于低频下PSRR的提高。基于5 V-0.35μm CMOS工艺设计,采用cadence仿真软件进行仿真验证。仿真结果表明,在100 kHz、10 kHz、1 kHz、100 Hz频率下,PSRR分别可达到-66、-85、-96和-97 dB。在不同的负载下,输出噪声在10 Hz～100 kHz频段不超过10μVrms,重载(250 mA)时的输出噪声最低可达到7.5μVrms,可用于便携式医疗电子设备。     

一种低噪声高PSRR的LDO线性稳压器

介绍了 LDO线性稳压器的系统组成原理,分析了系统的电源电压抑制比(PSRR)以及噪声与电路结构的关系,在此基础上,对LDO的核心电路模块进行了设计,并基于0.5μm标准CMOS工艺,运用Cadence平台进行了模拟仿真和验证.测试结果表明:该LDO的PSRR最低约为-45 dB@1 MHz,最高约为-75 dB@217 Hz;输出电压噪声在10 Hz频率以下约为0.78 μV(P-P),在10 Hz至l00 kHz频率范围内约为0.1 μV(RMS),能满足低噪声和高PSRR应用的要求.     

一种高电源抑制比的CMOS带隙基准电压源

设计了一种采用前调整器的高电源抑制比的CMOS带隙基准电压源.基于CSMC 0.5 μm标准CMOS工艺,分别对有前调整器与没有前调整器的CMOS带隙基准电压源进行了设计与仿真验证.仿真结果显示,采用前调整器的带隙基准在100 Hz、1 kHz、100 kHz处分别获得了-117.3 dB、-106.2 dB、-66.2 dB的高电源抑制比,而没有采用前调整器的CMOS带隙基准在100 Hz、1 kHz、100 kHz处仅分别获得了-81.8、-80.1、-44.9 dB的电源抑制比;在-15 ～90℃范围内,采用前调整器的带隙基准的温度系数为6.39 ppm/℃;当电源电压在2.2 ～8 V变化时,采用调整器的带隙基准的输出电压变化仅9.73μV.     

LDO稳压器中动态频率补偿和限流保护的研究

.文章针对LDO稳定性的问题,提出了一种内部动态频率补偿电路,使LDO线性稳压器的稳定性不受负载电容的等效串联电阻的影响,其单位增益带宽也不随负载电流变化而改变,大大提高了瞬态响应特性;采用Hynix 0.5μm CMOS工艺模型对电路进行仿真;此外,该电路在实现动态频率补偿的基础上又加入了系统的过流保护功能,当负载电流大于限制电流时,LDO不能正常工作;当负载电流小于限制电流时,又自动恢复到正常工作状态。     

1～9 GHz超宽带温度补偿低噪声放大器的设计

超宽带低噪声放大器是可重构射频前端、宽带相控阵雷达必需的芯片,其性能直接影响系统的灵敏度.展示一款集成温度补偿有源偏置电路的超宽带低噪声放大器,该放大器采用新型温度补偿有源偏置电路,能有效地降低工作环境温度变化导致的增益波动;同时,通过带宽扩展技术提高晶体管高频增益,实现9倍频程的工作带宽.该款芯片基于0.15μm GaAs pHEMT工艺设计制造,尺寸为2 mm×1.2 mm.测试结果表明,该低噪声放大器在5 V工作电压下,功耗为125 mW;工作频率为1～9 GHz,频带内噪声系数小于1 dB,增益大于25 dB,输入输出回波损耗小于-10 dB,输出1 dB压缩点大于10 dBm;在-55～125℃工作环境下,芯片增益波动小于1 dB.     

一种应用于LDO的温度保护电路设计

温度保护电路是LDO芯片的重要组成部分,能够保证LDO及其负载电路工作在安全温度区间内,避免温度过高而导致芯片损坏。提出了一种应用于LDO的温度保护电路,使芯片工作温度过高时自动关闭供电通路。所提出的温度保护电路利用双极晶体管基极-发射极电压的温度特性,当温度过高时将比较器状态翻转,输出控制信号控制调整管的栅极电压。本电路采用SMIC 0.18μm CMOS工艺进行电路设计并用Spectre软件进行仿真验证,结果显示本电路能够实现130℃关断LDO,温度下降到105℃重启LDO恢复工作,温度迟滞为25℃,工艺角仿真结果显示该电路工艺稳定性良好。     

应用于眼压信号检测的低噪声前置放大器设计

基于SMIC 180nm CMOS工艺,设计并实现了一款应用于眼压信号检测系统的低噪声前置放大器.该放大器使用二极管连接的MOS管实现GΩ级别的大电阻,在反馈回路中该伪电阻与反馈电容并联在低频段产生高通截止点以抑制直流失调电压和低频噪声,达到较好的噪声性能.后仿真结果显示:低噪声前置放大器的直流增益为40dB,有效带宽从0.25Hz到46kHz,在低频频率100Hz处的等效输入噪声为197.3nVrms,采用1.8V的电压供电,核心电路功耗为32.4μW,芯片面积为0.75mm×0.62mm.     

一种用于光电标签的高电源抑制比的低压差线性稳压器设计

高电源抑制比低压差线性稳压器(LDO)采用UMC 0.18μm标准CMOS工艺进行流片,电路中采用偏置电流提升技术、偏置复用等技术来降低LDO的功耗.为保证LDO的稳定性,电路采用密勒补偿技术增强系统的相位裕度.同时,采用前馈结构来提高在低静态电流时LDO的瞬态响应.输入电压为光电池所提供的2 V电压,输出电压为1.8 V,该稳压器的最大负载电流约为13 m A.当负载电流为2 m A时,电源抑制比约为-67d B,其带宽在6 k Hz左右.稳压器的静态电流约为32.2μA,芯片面积为320×224μm~2.     

适用于OTA-C滤波器的高线性OTA的设计

设计了一种适用于OTA-C滤波器的高线性运算跨导放大器(OTA).该OTA采用新型的乘法器输入级,以获得大的线性跨导输入范围;采用一种新的共模负反馈(CMFB)策略,将主放大器输出电压线性压缩后再引入CMFB电路,以改善传统CMFB结构对OTA输出线性范围的限制.在SMIC.35 μm标准CMOS工艺下仿真,结果显示:输入级的线性跨导差分输入电压范围达到了—2～2 V,等效跨导在1 μS时,直流(DC)开环增益达到了76 dB,共模抑制比(CMRR)为140 dB,电源抑制比(PSRR)为144 dB.基于这种OTA设计了OTA-C二阶低通巴特沃斯滤波器.通过调节OTA的跨导,滤波器在1 pf的负载电容下的截止频率从11 kHz变化至419 kHz;当截止频率为100 kHz时输出为3 Vp-p@100 kHz时的总谐波失真(THD)为—47 dB.     

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.     

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.     

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.     

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.     

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.     

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