直流电源由单变双的几种方法

目前不少集成电路采用单电源工作,简化了电源,但仍有不少电路需要正负电源才能工作。例如高性能的DAC（数模转换器）和ADC（模数转换器）的I/V（电流／电压）变换器电路、V／F（电压／频率）或F/V（频率／电压）变换电路、高性能运算放大器和电压比较器电路等等。对于有多种电源轨的系统或者有多个对称绕组的工频电源变压器来说,正负对称电源当然不是问题,对于只有一个次级绕组的电源变压器来说,采用图1所示的电路就可以很方便的得到正负对称的双电源,要得到低噪音和低纹波电源,可以加上有源电子有源滤波器或者采用π型电感滤波电路都是可以的,视需要的输出电流而定。     

基于∑-△ ADC的低功耗运算放大器设计

介绍了一种用于∑-△ADC的低功耗运算放大器电路.该电路采用全差分折叠-共源共栅结构,采用0.35 μm CMOS工艺实现,工作于3 V电源电压.仿真结果表明,该电路的动态范围为80 dB、直流增益68 dB、单位增益带宽6.8 MHz、功耗仅为87.5 μW,适用于∑-△ ADC.     

基于∑-ΔADC的低功耗运算放大器设计

介绍了一种用于∑-ΔADC的低功耗运算放大器电路。该电路采用全差分折叠-共源共栅结构,采用0.35μm CMOS工艺实现,工作于3 V电源电压。仿真结果表明,该电路的动态范围为80 dB、直流增益68 dB、单位增益带宽6.8 MHz、功耗仅为87.5μW,适用于∑-ΔADC。     

ADC外围电路的设计

ADC外围电路的设计通常包括模拟电路、数字电路和电源电路的设计。为了满足ADC的需要,ADC外围电路的设计重点是输入放大信号,为了使其充分发挥整体性能,必须在ADC转换期间保持输入电压的稳定;为了消除模拟多路开关因阻抗不匹配和转换阶跃信号变化对ADC输入及采样阶段的影响,需在多路开关与ADC之间加接高输入阻抗的电压跟随器,并待阶跃变化稳定后,再让采样保持电路进入采样阶段;为了满足微控制器对时序的要求,必须选择恰当的接口形式。此外,采用良好的接地方式与电压去耦方法,可以避免模拟信号和数字信号受到噪声干扰,也可避免两种信号产生互相干扰。为了防止噪声对数字信号的影响,还使用了相应的隔离方式。     

CMOS带隙基准电压源的设计

许多模拟电路需要性能较好的带隙基准电压源,如ADC,DAC等.对工艺、电源电压、负载变化不敏感的带隙基准电压源在模拟电路中得到了广泛的应用.现详细分析并说明了设计这样的带隙基准电压源电路需要考虑的问题.     

一种12位50MS/s CMOS流水线A/D转换器

采用TSMC 0.18μm 1P6M工艺设计了一个12位50 MS/s流水线A/D转换器（ADC）。为了减小失真和降低功耗,该ADC利用余量增益放大电路（MDAC）内建的采样保持功能,去掉了传统的前端采样保持电路;采用时间常数匹配技术,保证输入高频信号时,ADC依然能有较好的线性度;利用数字校正电路降低了ADC对比较器失调的敏感性。使用Cadence Spectre对电路进行仿真。结果表明,输入耐奎斯特频率的信号时,电路SNDR达到72.19 dB,SFDR达到88.23 dB。当输入频率为50 MHz的信号时,SFDR依然有80.51 dB。使用1.8 V电源电压供电,在50 MHz采样率下,ADC功耗为128 mW。     

一种用于高速高精度ADC的电压基准源设计

针对电压基准源对流水线结构的高速高精度ADC的性能影响进行了建模分析,提出了一种低压条件下具有低温度系数和较高电源抑制比的电压基准源电路。该电路采用简单的二阶曲率补偿技术,并加入了PSR提高电路和启动电路。同时给出了采用TSMC 1．8V0．18μm标准CMOS工艺和Hspice仿真软件的仿真结果。     

用于流水线ADC的全差分参考电压电路

为了实现流水线ADC的带隙基准电压低于1 V和降低参考电压电路的功耗,提出了一种新的全差分参考电压电路。在传统带隙基准的基础上,该参考电压电路增加了MOS管基-射极电阻,可根据电阻的比例系数来调节输出带隙基准电压。采用电流模电路,实现了单端信号转差分信号,结构简单。采用TSMC 0.18 μm CMOS工艺进行设计与仿真,结果表明,温度为25 ℃时,该电路的参考电压VREFP和VREFN分别为1.156 V和0.656 V。在-40 ℃~125 ℃范围内变化时,参考电压的波动小于6 mV,温度系数小于4.6×10-5/℃。低频时,电源抑制比为115 dB。该参考电压电路应用于高清视频信号处理的流水线ADC中,能实现170 MS/s、10位精度的数模转换。     

14位50MS/s100mW0.18μm CMOS流水线ADC

实现了一种14位40MS/s CMOS流水线A/D转换器(ADC)。在1.8V电源电压下,该ADC功耗仅为100mW。基于无采样/保持放大器前端电路和双转换MDAC技术,实现了低功耗设计,其中,无采样/保持放大器前端电路能降低约50%的功耗,双转换MDAC能降低约10%的功耗。该ADC采用0.18μm CMOS工艺制作,芯片尺寸为2.5mm×1.1mm。在40MS/s采样速率、10MHz模拟输入信号下进行测试,电源电压为1.8V,DNL在±0.8LSB以内,INL在±3.5LSB以内,SNR为73.5dB,SINAD为73.3dB,SFDR为89.5dBc,ENOB为11.9位,THD为-90.9dBc。该ADC能够有效降低SOC系统、无线通信系统及数字化雷达的功耗。     

应用于∑△ ADC的带隙基准源的设计

基于标准n阱0.6μm CMOS工艺条件,设计了一种用于高阶∑△ADC的基准源结构.该电路在传统带隙基准电路的基础上,采用三个纵向晶体管串联的形式减小运放输入失调电压对基准电压的影响同时采用高增益运放来降低基准电流的失配.另外设计了启动电路以确保基准电路能正常工作.仿真结果表明此电路电源抑制比为73 dB,温度系数为9.6×10-6/℃.经过对系统的分析与验证,该电路完全满足高阶∑△ADC对其性能的要求.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.