Lab on the Web: Running Real Electronics Experiments via the Internet / Edition 1 by Tor A. Fjeldly, Michael S. Shur
Together with the internet site, this book is ideally suited for independent and remote study Web site is kept to date and guest educational institutions are...
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Together with the internet site, this book is ideally suited for independent and remote study Web site is kept to date and guest educational institutions are invited to join in creating their own lab modules on different device aspects First such program Reputation of the authors who are leaders in the field of semiconductor electronics
About the Author
TOR A. FJELDLY received his MSc from the Norwegian University of Science and Technology and his PhD from Brown University. He is a professor at UniK-University Graduate Center and the Norwegian University of Science and Technology, an adjunct professor at the University of Oslo, a visiting professor at Rensselaer Polytechnic Institute, as well as a Fellow of the IEEE and an elected member of the Norwegian Academy of Technical Sciences.
MICHAEL S. SHUR received an MSEE (with honors) from St. Petersburg Electrotechnical Institute and a PhD in Physics and a doctor of science degree from A. F. Ioffe Institute. From 1989 to 1996, he was John Money Professor at the University of Virginia, where he served as director of the Applied ElectroPhysics Laboratory. He is currently Roberts Professor of Solid State Electronics, Professor of Physics, Professor of Information Technology, and Director of the Center for Broadband Data Transport Science and Technology at Rensselaer Polytechnic Institute. A Fellow of IEEE and Fellow of APS, he is the author of Introduction to Electronic Devices and coauthor, with Prof essor Fjeldly and Trund Ytterdal, of Introduction to Device Modeling and Circuit Simulation, both published by Wiley.
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Lab on the WebRunning Real Electronics Experiments via the Internet
John Wiley & SonsCopyright © 2003 John Wiley & Sons, Inc.
All right reserved.
Chapter OneELECTRONICS LABORATORY EXPERIMENTS ACCESSIBLE VIA INTERNET
T. A. FjeldlyUnik-University Graduate Center Norwegian University of Science and Technology, N-2027 Kjeller, NorwayM. S. ShurRensselaer Polytechnic Institute, Troy, New York 12180
Remote-distance, interactive learning is an important emerging educational trend. The Internet is an ideal medium for remote instruction purposes, offering interesting possibilities for disseminating educational material to students, both locally and as part of remote education. Its ubiquity and protocol standards make data communication and front-end graphical user interfaces relatively easy to implement.
Laboratory experiments are an indispensable part of engineering education that until recently have been considered impractical for distance learning. However, the advances over the last decade in the Internet, World Wide Web technologies, and computer-controlled instrumentation presently allow net-based techniques to be utilized for setting up remote laboratory access, permitting remote education to be enhanced by experimental modules.
Currently, remote educational laboratories over the Internet, particularly in the area ofelectronics and instrumentation, have become operational at several sites (see Shen et al., 1999; Gustavsson, 2001; Geoffroy et al., 2001; Berntzen et al., 2001; del Alamo et al., 2002; Wulff et al., 2002; Söderlund and Jeppson, 2002). With these facilities, novel pedagogical uses have also emerged, including experimental demonstrations to enhance traditional classroom lectures, adding laboratory modules as homework exercises in regular courses, establishing studio classrooms where students do supervised laboratory exercises on individual terminals, and encouraging individual discovery activities among students. All of these activities fit nicely into a modern strategy for distance learning.
In a broader perspective, the Internet lab technology can be offered to remote students on a global scale, removing a major obstacle for establishing a boundless and complete remote engineering education curriculum. As an added benefit, such systems may offer students the opportunity to work with sophisticated equipment of the kind they are more likely to find in an industrial setting and that may be too expensive for most schools to purchase and maintain for educational purposes.
Our work on remote lab systems started in 1997 as a collaboration between Rensselaer Polytechnic Institute (RPI) in Troy, New York, and the Norwegian University of Science and Technology (NTNU) in Norway. Presently, we operate three sites: AIM-Lab (Automatic Internet Measurement Laboratory) at RPI, LAB-on-WEB at UniK-University Graduate Center near Oslo, Norway (affiliated with NTNU and the University of Oslo), and NGL (Next Generation Laboratory) at NTNU in Trondheim, Norway. At these sites, we have explored and developed different system technologies, as will be explained below and in Chapter 4 of this book. However, all systems are based on a server-client architecture, where the clients (students) communicate over the net with a server and its experimental setup using modern web browsers. For the most part, we have developed dedicated system software that does not require any download by the client, but in some cases optional solutions are offered based on software that can be downloaded from the Internet for free.
Biased by our background in physics and electronics, we have emphasized the establishment of laboratories dedicated to semiconductor device characterization, with experiments performed on microelectronic test chips and on commercial devices. Our labs have been used in courses on semiconductor devices and circuits at the senior or first-year graduate level at all our institutions. At our sites in Norway and the United States, we have jointly investigated several practical solutions for establishing such laboratories. Central objectives were to create a user-friendly and efficient technology for interactive, on-line operation of the lab experiments, to allow communication with minimum overhead, to provide a functional client interface, to establish a variety of experiments, and to allow flexibility in configuring experiments from the client side.
The AIM-Lab site at RPI is based on a TCP/IP (Transmission Control Protocol/Internet Protocol) communication solution, which uses a Java applet on the client side. This was achieved by means of a JVM (Java virtual machine) in the web browser that can download and execute Java code. The client sees a pop-up window that provides interaction and communication directly with the server. This system is described in Section 1.2.
LAB-on-WEB at the UniK site relies on modern web and instrument control technologies, including COM+ (component object model with extensions), ASPs (active server pages), ISAPI (Internet server application programming interface), and LabVIEW (Laboratory Virtual Instrument Engineering Workbench) version 6i from National Instruments. Advanced functionalities of modern web browsers are utilized, allowing the system to communicate in terms of XML (eXtensible Markup Language) and SVG (scalable vector graphics). SVG is a vector-based, open-standard file format developed by the World Wide Web Consortium, which represents a new generation of dynamic, data-driven, and interactive graphics. The LAB-on-WEB system is described in Section 1.3.
At the NGL site at NTNU, Microsoft's new .NET technology was adopted. This solution is described in Chapter 4 of this book.
In Section 1.4, we discuss by way of examples some of the experiments available at AIM-Lab and LAB-on-WEB.
This presentation emphasizes the technological aspects of our remote lab systems and the specific experiments offered. We have so far not performed systematic evaluations of the educational benefits derived from using these labs. Obvious benefits to the students are apparent in terms of availability and ubiquity, likewise the presentation of "live" lab demonstrations in the classroom. Our subjective impressions are that the students show a positive interest and curiosity, and we register a positive attitude to the freedom offered in terms of scheduling their lab sessions.
1.2 AIM-LAB AT RPI
1.2.1 System Architecture
The AIM-Lab system architecture is shown in Figure 1.1. The server, written in Microsoft Visual C++, includes two main components. One of them is a TCP/ IP server socket that receives commands sent over the Internet. The second component, the driver interface layer (DIL), interfaces between the instrument driver and the higher levels of the server (Shen et al., 1999; Fjeldly et al., 2000). The DIL sends the commands to the instrument driver, which uses the GPIB (general-purpose instrument bus) Institute of Electrical and Electronics Engineers (IEEE) 488.2 standard protocol to drive the instruments. A third component is the GUI (graphical user interface) for the instructor. This interface on the server side allows the instructor to monitor and control the server process as well as modify the configuration of the instrumentation.
The client side is a Java applet that initially appears as a push button on the AIM-Lab web page. By pressing the button, the applet creates a pop-up window that provides the GUI interface to the user. The client's command generator issues commands according to the parameter set specified by the user and sends them via the TCP/IP client socket to the server. The experimental results sent back by the server are then handled and displayed in the client window.
In AIM-Lab, Java is the programming language of choice on the client side, since it offers the flexibility of a GUI design, convenient network programming, and platform independence. The operation is achieved by means of a JVM in the client's web browser that can download and execute Java code. The client sees a pop-up window that, on the one hand, provides GUI interactions to the user and, on the other hand, communicates directly with the server. The GUI interface is created according to the information on the experiments received from the server upon client initialization.
The AIM-Lab system is designed to minimize the overhead of the data communication through the Internet, maximize the server performance and efficiency, ensure the data accuracy and integrity, and provide an easy access to the user. In order to maximize the server performance and efficiency, we developed the server as a Windows-based MDI (multidocument interface) application. This is a multiuser and multiexperiment environment with a task queue. For each user, it records all the commands and data in a dedicated document window.
The experiment requests are sent to the instrument driver in the order of receipt, and the resulting data are sent back accordingly. No experiment failure or error caused by the clients leads to a malfunction of the server. Any experiment that takes an exceedingly long time to finish (which might suggest a failure) is discarded and hence does not affect the other experiments. The server does not parse or interpret the commands. It assumes that the command generator of the client program correctly generates the commands. In case of an error, the server will discard the commands as described above. This reduces the processing overhead of the server and makes the server very flexible. When an instrument or a circuit is changed, the server sends the information about the change to all the running clients.
1.2.2 AIM-Lab Operation
The system provides easy access for the user and maximizes the speed of the on-line measurements. No file needs to be downloaded in order to perform the experiments, which is an advantage compared to other realizations in terms of speed and security. All the user has to do is to access the AIM-Lab website (nina.ecse.rpi.edu/shur/remote/) and start the client window by pressing a button. The user can set up experiments and send experiment requests by activating pop-up dialog boxes. The results of the measurements are displayed in the client window, and the user can navigate between the experimental plots with ease. The resulting data and plots can be saved using Copy and Paste functions of the Windows and Unix systems.
The communication overhead is minimized by sending only the absolutely necessary information via the Internet and by organizing the generated commands, data results, and server messages in the most compact format. We have tested the system off-campus using a commercial 56-kbps modem. According to our test, the time needed to access the website and start the client window is about 50 sec. It takes less than 10 sec for the system to perform a complete experiment, including sending commands and receiving and plotting the data.
The user accesses the AIM-Lab website using a standard web browser. When logging in, the server application is launched and all information on the available experiments is read from a library file and sent to the client. The client window behaves as a stand-alone application in which the user selects an experiment and specifies experimental parameters (e.g., voltage range, step size) in pop-up dialog boxes. Consecutive experiments can be set up and sent to the server without waiting for the previous experiment to finish. An experiment is initiated by activating the Start Experiment menu item in the Operation pop-up menu. Some of the client windows encountered are shown in Figure 1.2.
The instructions from the client are then sent via the TCP/IP client socket to the server, which runs the experiment and returns the experimental data to the client. The results are presented in the client browser window as columns of numerical data and a graph. The numerical data can be copied from the window for further processing by the user. As an example, Figure 1.3 shows the current-voltage (I-V) characteristics of an n-channel metal-oxide-semiconductor field effect transistor (MOSFET).
Java applets provide good control. However, unsigned applets make it awkward for the client to store and present data received from the server side and to transfer them to other applications (except by cut-and-paste) because of Java's security structure. A further problem with Java is that the functionality of an applet may vary between different browsers. While Java 2 has better support for the user interface, some of the new classes included in this version are not automatically compatible with JVM, requiring an additional plug-in to be installed in the browser. For many potential users, this is a problem, partly because of skepticism toward plug-ins and partly because of local security regulations in many organizations. Besides, the future support of Java is uncertain.
1.2.3 AIM-Lab Experimental Setup
220.127.116.11 Device Test Structures AIM-Lab is presently dedicated to the characterization of a group of test devices that includes a set of complementary metal-oxide-semiconductor (CMOS) devices and a set of light-emitting diodes (LEDs) made from different compound semiconductors. CMOS is the most important integrated circuit technology, far outselling all other semiconductor technologies, including bipolar, thin-film transistor (TFT), and compound semiconductor technologies. The importance and proliferation of CMOS necessitate a good understanding of its operation by very large scale integrated (VLSI) designers and users alike. The best way to teach the basics of CMOS technology is by a hands-on approach, which combines the basic theory of operation with measurements, parameter extraction, and CMOS circuit simulation (see Lee et al., 1993; Fjeldly et al., 1998).
AIM-Lab presently allows experiments to be performed on the CMOS test chip shown in Figure 1.4. This chip, designed, fabricated, and characterized by our group, includes two arrays of NMOS (n-channel MOSFET) and PMOS (p-channel MOSFET) devices with a wide range of gate geometries for the purpose of investigating the scaling properties of the devices. In each array, all source electrodes are interconnected, so are all the gates and all the substrate electrodes. Only the drain electrodes have separate contact pads. Additional diagnostic structures are also available, including a loaded and an unloaded ring oscillator.
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Table of Contents
1. Electronics Laboratory Experiments Accessible via Internet (T.A. Fjeldly and M.S. Shur).
2. MIT Microelectronics WebLab (J.A. del Alamo, et al.).
3. Instrumentation on the Web (T. Zimmer, et al.).
4. Next-Generation Laboratory: Solution for Remote Characterization of Analog Integrate Circuits (C. Wulff, et al.).
5. Remote Laboratory for Electrical Experiments (I. Gustavsson).
6. Remote Laboratory: Bringing Students Up Close to Semiconductor Devices (A. Söderlund, et al.).
What People are Saying About This
"…a groundbreaking resource for remote study of interactive electronics applications." (IEEE Solid-State Circuits Society Newsletter, January 2004)
"I would recommend this book for any academic electrical or electronics collection, especially those at institutions where distance and online learning play an important role." (E-STREAMS, July 2004)
“...offers an excellent introduction to and a how-to-use tutorial...highly recommended.” (Choice, Vol. 41, No. 7, March 2004)