一种宽电压输入范围电流可调型LED恒流驱动芯片设计

基于0.5μm CMOS工艺设计了一款LED恒流驱动芯片。该设计实现了9V~40V的输入电压,同时通过外置反馈电阻实现了电流的可调,电流范围可从10m A变化至80m A;通过验证实现了在不同工艺角下,当温度不变而输出电压从1V变化到8V的情况下,10m A和80m A电流变化误差均约±0.6%;在不同工艺角下,当输出电压不变而温度从-40℃变化到125℃时,10m A电流变化误差约为±1.5%,80m A电流变化误差约为±1.15%。设计主要包括校准器、带隙基准电路、输出运放结构以及过温保护电路,并对各个电路做详细分析。     

精密CMOS带隙基准及过温保护电路设计

设计了一款带有软启动电路的精密CMOS带隙基准源,并且利用PN结正向导通电压具有负温度系数和基准源提供的偏置电流具有正温度系数的原理实现了过温保护功能。采用UMC公司0.6μm 2P2M标准CMOS工艺进行设计和仿真,HSPICE模拟表明带隙基准的输出电压为1.293 V,且具有较高的精度和稳定性。在1.5V~4.0V的电源电压范围内基准随输入电压的最大偏移为0.27 mV;在-40℃~120℃的温度范围内,基准随温度的变化约为4.41 mV;基准的输出启动时间约为25μs;当工作温度超过160℃时过温保护电路将输出使能信号关断整个系统。     

一种高灵敏度过温保护电路的设计

提出了一种应用于LED驱动器的过温保护电路。该电路的温度检测模块通过调节电流镜两条支路上的电阻比值来提高温度系数,输出级采用共源共栅结构,具有温度系数高、受工艺参数变化影响小、电压稳定好等优点。基于CSMC 0.5 μm CMOS工艺,采用Hspice软件对电路进行仿真,结果表明,温度检测模块的工作范围为－45 ℃~135 ℃,CTAT输出电压线性度良好,最大偏差小于2%。当电源电压为5 V时,负温度系数达到11.2 mV/℃,温度感应转变时间小于20 ns;该过温保护电路能较好地抑制电源电压波动引起的阈值点漂移,其漂移系数仿真值小于2.5 ℃/V。     

电流随温度自适应调节的LED驱动电路

针对传统LED驱动芯片不适用于大功率连续照明的问题,设计了一种电流随温度自适应调节的LED驱动电路。该电路具备过温滞回关断保护作用。基于CSMC 0.5 μm工艺,Spectre仿真结果表明,当电源电压正负波动10%时,恒流输出波动小于1.1%;当系统温度在0 ℃~83 ℃变化时,恒流输出变化小于0.28%;在83 ℃~103 ℃之间,调控输出电流可调幅度为93 mA,这种幅度变化不会被人眼发觉有明显光变;当温度升高到106 ℃时,过温关断保护电路开启,关断整体电路输出,直到温度降回69 ℃后,LED驱动电路又重新开启。     

一种USB电源管理芯片双门限限流保护电路

采用折返式电路,设计了一种适用于USB电源管理芯片的双门限限流保护电路。通过改变参考电流,进而改变比较器参考电压的方式,使系统在发生过流时输出恒定电流,发生短路时实现门限降低,以达到更低的恒定输出电流。采用UMC 0.5 μm CMOS工艺,运用Cadence和Hspice进行仿真验证,温度在-40 ℃～120 ℃变化时,过流门限和短路门限仅变化2.1%和1.5%。不同工艺角下,均满足系统要求。     

两种低功耗新型过温保护电路的设计

电源管理芯片中过温保护电路用来检测芯片的温度。当温度过高时,过温保护电路输出保护信号,使芯片停止工作,以免温度过高而损坏芯片。为了实现上述过温保护电路功能,提出了两种新型的过温保护电路,不但能够精确地检测芯片的温度,并且功耗很低。采用0．5μm N-阱CMOS工艺的方法,进行电路设计,并使用CadenceSpectre工具进行了仿真实验验证。仿真实验结果表明两种电路仅消耗3μA的电流就能够实现精确的温度检测,其具有较强的适应性,高灵敏度和高精度的特点,应用前景比较广泛。     

基于迟滞比较器的过热保护电路设计

为了防止芯片过热,提高芯片可靠性和稳定性,采用0.5μm CMOS工艺,设计了一种具有迟滞比较器的过热保护电路。由于采用了折叠式运放,使得比较器输入范围更大,灵敏度和迟滞性能更好。利用Cadence Spectre仿真工具对电路进行了仿真,结果表明电源电压为4.5～7 V时,过温保护阈值变化量极小,表现出输出信号对电源的良好抑制。当温度超过130℃时,输出信号翻转,芯片停止工作;温度降低至90℃时,芯片恢复工作。此电路可以通过调整特定管子的尺寸而控制两个阈值电压的大小,从而避免热振荡的发生。     

一种基于BCD工艺的汽车电压调节器芯片设计

针对目前车用电压调节器体积大、稳定性差和寿命短等问题,设计了一款用于汽车的电压调节器芯片。该芯片通过PWM技术调整发电机励磁绕组的平均励磁电流,稳定了发电机输出电压。同时,该芯片集成了低温漂、高精度的电压基准源与电流源,还具有欠压锁定与过温保护电路,提高了系统可靠性。芯片基于0.5 μm BCD工艺进行设计,采用Cadence Spectre进行仿真。仿真结果表明,该芯片工作电压是720 V,静态电流仅为472 μA,电压调节范围1020 V,基准电压1.16 V,工作温度范围-40125 ℃,温度系数8.4 ppm·℃ ^-1,且当发电机输出电压波动时,该芯片可使输出电压稳定。     

高阶曲率补偿低温漂系数带隙基准电压源设计

设计了一种高阶曲率补偿低温漂系数的CMOS带隙基准电压源,采用自偏置共源共栅结构,降低了电路工作的电源电压。采用电流抽取电路结构,在高温阶段抽取与温度正相关电流,低温阶段抽取与温度负相关的电流,使得电压基准源在整个工作温度范围内有多个极值点,达到降低温漂系数的目的。在0.5μm CMOS工艺模型下,Cadence Spectre电路仿真的结果表明,在–40~+145℃范围内,温度特性得到了较大的改善,带隙基准电压源的温漂系数为7.28×10~(–7)/℃。当电源电压为2.4 V时电路就能正常工作。     

一种高精度带隙基准源和过温保护电路

设计了一种适用于P阱CMOS工艺的高精度带隙基准源及过温保护电路。基准源信号输出由两路电流相加实现：一路是正比于双极晶体管的发射极一基极电压的电流(IVBE)，另一路是基准源内产生的正比于绝对温度的电流(IPTAT)；同时，利用这两路电流的不同温度特性，通过直接电流比较的方法，简单地实现了高精度的过温保护电路。     

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.     

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.     

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.     

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.     

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.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks