一种芯片内部稳压电源的实现

介绍和分析了一种用于PWM控制器内部的稳压电路,采用双极线路结构和4μm工艺。经过PSPICE仿真,它具有0．176mV／V的稳压系数和60dB的纹波抑制比和较低温度系数。     

On a wing and a prayer

Aircraft giants Boeing and Airbus are pinning their hopes on very different visions of how air travel will evolve in the coming decade.     

Building a in a flash supercomputer

A flash mob is a group of strangers, organized over the Internet, that comes together briefly, acts out a predetermined scenario-often something as simple as clapping for 30 seconds-and then disperses. A supercomputer is a very fast and powerful computer that outperforms most mainframes, at a cost, typically, of millions of dollars. Can a flash mob build a supercomputer? It can sure try, and so it did on 3 April at the University of San Francisco's Koret athletic center. The goal was to run the Linpack benchmark, a standard method of assessing the speed of supercomputers, to achieve a speed of at least 403 gigaflops (billion floating point operations per second). This would be fast enough to earn the system a place on the list of the world's fastest 500 supercomputers. The goal was not reached. The group reached just 180 gigaflops before it was time to pack up the computers and go home. However, even though the San Francisco effort fell short of speed goal, it did ignite imaginations.     

一年之间，物换星移

去年的这个时候,供货商们还在为生存而挣扎。如今,2009年的年报已经公布,许多供应商的年报业绩之好,就连最乐观的分析师也始料未及。这种变化的原因很简单：供应商们大幅削减成本,接下来是强劲的需求,这又导致了随后高企的设备利用率。     

Converting a Display Screen into a Touchscreen

A method is presented to convert any display screen into a touchscreen by using a pair of cameras. Most state of art touchscreens make use of special touch-sensitive hardware or depend on infrared sensors in various configurations. We describe a novel computer-vision-based method that can robustly identify fingertips and detect touch with a precision of a few millimeters above the screen. In our system, the two cameras capture the display screen image simultaneously. Users can interact with a computer by the fingertip on the display screen. We have two important contributions: first, we develop a simple and robust hand detection method based on predicted images. Second, we determine whether a physical touch takes places by the homography of the two cameras. In this system, the appearance of the display screen in camera images is inherently predictable from the computer output images. Therefore, we can compute the predicted images and extract human hand precisely by simply subtracting the predicted images from captured images.     

Cooperative control of a human and a robot manipulator for positioning a cart on a frictionless plane

Robots may be expected to execute some tasks in cooperation with humans. Control systems for such robots should be appropriate to adapt to human characteristics in order to successfully accomplish the task. Pushing a cart on a frictionless plane in cooperation with a human is a basic example to such a task. To control the motion of an object from one point to another on a frictionless plane is impossible by only pushing in one direction without supporting it in the opposite direction, since as soon as the force is applied, the object will move without stopping its motion. In this paper, compliant cooperative positioning of a cart on a frictionless plane by a human and a manipulator is proposed using impedance control method with the parameters obtained from human–human cooperation.     

Analysis of a coaxial-to-waveguide adaptor including a discendedprobe and a tuning post

A field matching analysis of a coaxial-to-waveguide adaptor incorporating a disc-ended probe and a tuning post is presented. In this analysis, the tuning post is considered as a short-circuited second probe. A computer algorithm for calculating the input impedance of this structure is developed. This algorithm is used to investigate and improve the operation of a commercially available coaxial-to-waveguide adaptor     

Transmission-Line Properties of a Strip on a Dielectric Sheet on a Plane

The subject is a strip Iine formed of a strip and a parallel ground plane separated by a dielectric sheet (commonly termed "microstrip"). Building on the author's earlier papers all the significant properties are formulated in explicit form for practical applications. This may mean synthesis and/or analysis. Each formula is a close approximation for all shape ratios, obtained by a gradual transition between theoretical forms for the extremes of narrow and wide strips. The effect of thickness is formulated to a second-order approximation. Then the result is subjected to numerical differentiation for simple evaluation of the magnetic-loss power factor from the skin depth. The transition formulas are tested against derived formulas for overlapping narrow and wide ranges of shape. Some of these formulas are restated from the earlier derivations and others are derived herein. The latter include the second-order approximation for a narrow thin strip, and a close approximation for a narrow or wide square cross section in comparison with a circular cross section. Graphs are given for practical purposes, showing the wave resistance and magnetic loss for a wide range of shape and dielectric. For numerical reading, the formulas are suited for programming on a digital pocket calculator.     

基于智能手机压电基片上微液滴位置分析章

为了降低微流分析成本,该文提出了基于智能手机检测压电基片上目标微液滴方法,并开发出相应的应用软件,通过分析微液滴颜色信息和几何信息定位目标微液滴位置,结合分析时间获取微液滴输运速度。为验证提出方法的正确性,以5 μL黑色墨水溶液微液滴为研究对象,进行压电基片上微液滴识别和位置分析实验。结果表明,该文所提方法和开发的应用软件可识别和定位压电基片上微液滴,在功率为27.5 dBm时,第2~10 s段内微液滴输运速度为0.416 mm/s。     

利用悬臂梁将均匀周期光纤光栅变为啁啾光纤光栅

利用均质、等厚及等腰梯形的悬臂梁,对刚性粘贴其表面的光纤光栅的布喇格反射中心波长在1557．68～1564．2nm范围内进行了线性调谐,同时带宽为外0.52nm的均匀周期的光纤光栅被调谐成带宽为2．52nm的啁啾光栅,且啁啾量可调。随着带宽的增加,反射谱的峰值功率呈减弱的趋势。     

量子点中极化子性质:压缩态变分法

利用单模压缩态变分法得到了在电子-体纵光学声子全耦合条件下抛物量子点极化子的基态能量及电子周围平均声子数的表达式。所采用的变分方法是基于逐次正则变换的变分方法,变换处理了包含经常被忽略的声子产生湮灭算符的双线性项。在电子-体纵光学声子全耦合条件下,讨论了受限长度与抛物量子点极化子的基态能量及电子周围平均声子数之间的依赖关系。     

The measurement of a large antenna using a spacecraft as a receiver

Two computational methods for obtaining the gain pattern of a large antenna using power levels recorded by a spacecraft are developed from the transmission equation. Nominally, the large antenna is linearly polarized while the spacecraft's receiving antennas are circularly polarized. Since the spacecraft has no attitude control system, the orientation of the receiving antennas is not known a priori nor its orientation the same from orbit to orbit. The first method relies on an independent spacecraft attitude determination system to furnish the orientation of the receiving antennas. It combines this information with receiving-antenna gain measurements to give the power level of the incident radiation. Losses due to polarization mismatch are taken into account, but polarization loss factors are not actually computed. The second method relates simultaneous measurements made by separate channels with separate receiving antennas. By solving a system of equations numerically, one can determine the direction of the incident radiation as well as its power level. This alleviates the need for an attitude determination system. These methods originated in the operations of the spacecraft NUSAT1 (northern Utah Satellite)     

Analysis of a coupled slotline on a double-layered substratecontaining a magnetized ferrite

Nonreciprocity in the propagation characteristics of the even and odd modes in magnetized-ferrite-loaded double-layered coupled slotlines is studied. The analysis is based on Galerkin's method applied in the Fourier transform domain. Numerical results are presented for various values of structural parameters. As a result, it is found that the waveguide structures studied have sufficient nonreciprocity in propagation constants for isolators and four port circulators     

构建完整工业ADC接口的微控制器和调制器

设计师们通常使用0mA～20mA和0V～10V的隔离输入作为工业应用控制的信号.由隔离电源、Analog Devices AD7400调制器内置隔离及TexasInstruments MSP430微控制器共同为工业设计师要求的一种完整、隔离且可靠的模拟信号接口创建一种设计.     

用CPLD实现步进电机驱动器

本设计实例基于摩托罗拉(现为飞思卡尔)广为使用但已淘汰的SAA1042步进电机驱动器IC,用一片CPLD(复杂可编程逻辑器件)实现了步进电机驱动器,它也可以代替基于SAA1027或UCN5804B设计中的驱动器.     

Blocking in a system on a chip

With more and larger functions being implemented on a single piece of silicon, true systems on a chip are being created. At the physical level, this integration derives from progress in process technology. But from the circuit designers' viewpoint, tools and methods are less help than they might be. In effect, to construct a system on a chip means more than the integration of millions of transistors. A set of complicated and rapidly evolving technologies and standards for telecommunications, multimedia, and PCs must be mastered, too. Also, the software content of most electronic systems has been growing for several years and now often accounts for a major part of the final product and hence of the design effort. Since a system on a chip is a system, a design methodology for generating such complex ICs will frequently have to address the software as well as hardware needs. Further more, as the size and complexity of chips has grown, so too has the task of verification. Verifying the design of a chip containing a million gates of logic presents a formidable challenge of its own. The complexity of large designs calls for a shift in the design paradigm to one based on reusable, high-level building blocks. Currently, most functional blocks are created by hand and are seldom used again. Reusable blocks, though, are not enough. To deliver on the promise of more productivity and less time to market, designers need reinforcements-a methodology and tools with which to integrate the blocks efficiently, plus standards that support the creation of reusable blocks, their exchange, and their integration     

Analysis of a strip in a waveguide

An analysis and an experimental study of a strip in a transverse plane of a rectangular waveguide below cutoff are presented. This work is a preliminary step in analyzing a stripline-fed slot antenna array in which each stripline feed is enclosed in a rectangular waveguide below cutoff. A numerical method is developed to solve a “pseudo” mixed-potential integral equation for the current on the strip excited by a delta-gap source at some point along the strip. The Green's function for dipole sources in the rectangular waveguide is used in the spectral and spatial representations and Shanks' transform is employed to speed up the convergence of the doubly infinite series. Numerical and experimental results are presented for a monopole fed at one wall of a rectangular waveguide and for a bottom-fed and bottom-loaded strip in a rectangular waveguide     

对高速比较器中复位场效应管的研究

A high-speed comparator design based on regeneration architecture, which can be used in a flash ADC, is presented.A threshold-limit-speed effect（TLSE） which limits the speed of the comparator was discovered and studied in detail.The size of the reset-MOSFET was optimized to resolve the TLSE and make the comparator work at the maximal speed.The results were confirmed by simulation and the corresponding circuit was realized in a flash ADC design in SMIC 0.18-μm CMOS technology.The test result shows that the comparator can work well at 2 GHz and can even work up to 2.8 GHz while the power dissipation is 3.2 mW.