Researchers Develop "Ballistic Computing" Transistor
A team of US university researchers is working on a ballistic transistor that would mark a new approach to creating ultra-fast, energy-efficient chips.
University of Rochester professor Marc Feldman is the principle investigator for the team of experts in computer engineering, circuit design, computer architecture, and theoretical physics who are working on the ballistic deflection transistor (BDT).
The key to the BDT is a Y-shaped electrical junction with a nonconductive, triangular deflector block in the middle.
Researchers have developed a ballistic deflection transistor that promises to be fast and energy efficient. The BDT has a Y-shaped electrical junction with a triangular deflector block in the middle. The BDT launches an electron into the junction. The electron passes through an electrical field that pushes it slightly to one side or the other and then bounces off one of the deflector block's sides and down one part of the function to a left or right output port. This creates the ones and zeros of binary data. A voltage differential between the top and bottom of the system launches an electron through the transistor gates into the junction. The electron then passes through an electrical field that pushes it slightly to one side or the other. At this point, it bounces off one of the triangle deflector block's sides and down one part of the Y-junction to a left or right output port.
"This changes the voltage at the port," explained graduate student Quentin Diduck, who developed the BDT concept. "Electrons at a port reduce the voltage; the absence of electrons increases the voltage." This determines whether the electron represents a binary one or zero.
Using a deflector block, rather than electric current, to direct electrons is a major difference between BDT and other ballistic-transistor approaches, noted Feldman.
BDT technology addresses several problems with today's transistor approaches, which essentially generate binary ones and zeros by stopping and starting current flows.
First, BDTs don't use a constant flow of electricity—which uses power and generates heat—to move electrons through the system, as current transistors do. Instead, the energy from the initial electron launch and the passive deflector do much of the work, thereby consuming less power.
Also, as transistors get smaller, electrical leakage—and thus power consumption—worsens because gates become thinner and leak increasing amounts of current. BDTs use a non-traditional gate structure that causes less leakage.
Because they are energy efficient, they use lower voltages. For this and other reasons, they generate less noise that could interfere with accurate signal transmission.
The researchers say they are looking into using an indium gallium arsenide-indium aluminum arsenide substrate, whose material structure enhances electron flow and thereby improves performance. Thus, said Feldman, BDT-based chips could eventually run at terahertz speeds, rather than at several gigahertz as today's microprocessors do.
He said the transistors could be made with current fabrication technologies, which could make them attractive to chip makers.
The US National Science Foundation has given the BDT team $1.1 million to build a prototype and come up with a circuit design methodology and possible chip architectures.
This will require considerable work and must be done before the team could even consider the technology's commercialization, said Feldman.
Project Improves Mesh Networks
A new wireless-mesh-network technology promises to yield high performance with low energy consumption via an approach that could be useful in cell phones and other mobile devices.
BBN Technologies, a private research contractor, created the Joint Architecture Vision for Low Energy Networking (Javelen) approach with funding from the US Defense Advanced Research Projects Agency's (DARPA's) Connectionless Networks Program.
A mesh network is a collection of nodes that can communicate directly with one another without a central control hub. Nodes forward packets to their destination via multiple hops if necessary. This eliminates the need for a costly network infrastructure and enables fast and flexible network setup, potentially important in case of public emergencies.
However, said BBN scientist Jason Redi, because each node must leave its radio on at all times to listen for incoming signals, they use considerable energy. To conserve the limited energy supply in battery-operated nodes, mesh networks generally use low data rates.
To speed up mesh networks while conserving power, Redi explained, BBN built energy-efficient radios that separate the transmitter and receiver operations, so both aren't operating when only one is necessary. The radios can also quickly switch between states—off, idle, transmit, receive—and use the minimum amount of energy necessary for each.
BBN has added technologies that enable nodes to know which other nodes in a system are awake and ready to receive information and that synchronize their operations to maximize transmission efficiency.
Javelen mesh networks' data rate is 2 megabits per second, fast enough for multiple video streams. Its energy use is about 100 times less than equivalent military sensor networks, according to BBN.
DARPA has helped fund the project because it is interested in self-forming wireless networks," said Preston Marshall, a program manager with the agency's Strategic Technology Office. The BBN approach is particularly interesting because of its highly adaptable power-usage scheme, he explained.
"Clearly the military has interest in these kinds of things so that they can operate where there is no infrastructure or where you do not trust the infrastructure," said Redi.
Moreover, he added, service providers could implement Javelen networks in remote areas where infrastructure installation would be costly.
Javelen also could be used to network home devices and to extend battery life and enable the running of energy-hungry applications in mobile equipment.
BBN has no current plans to commercialize the technology but is interested in the possibilities, noted Redi.
Sun Makes Java Open Source
Sun Microsystems has begun releasing most of its popular Java technology as open source software. By mid-2007, Sun will release most of Java's source code—except for a small amount owned by other companies—under the GNU General Public License (GPL), version 2, which governs many types of open source software, including the Linux kernel.
This will let all programmers examine, modify, fix, or add features to Java's underlying code, as long as they make the work public and subject to the GPL (www.gnu.org/copyleft/gpl.html).
Sun is employing a classpath exception, which lets users build applications by combining code covered by the GPL with other code, without having to make the overall programs available under the license, explained open source pioneer Eric Raymond. He said this is necessary "in order not to frighten closed-source developers away from using Java."
Sun's move will not affect customers currently licensing the Java platform and won't change the Java Community Process, which lets interested parties help the company define future Java versions and features, said Rich Sands, Sun's community marketing manager for the Java Platform, Standard Edition (JavaSE).
Some users will want to continue licensing Java because they could work with the technology without having to deal with the GPL and could receive support and services from Sun, he noted.
Sun's upcoming open source release will include all of the Java platform, Micro Edition, at https://phoneme.dev.java.net.
The company will also soon make available the JavaSE's HotSpot virtual machine and javac compiler, at https://openjdk.dev.java.net, and all of the GlassFish open source Java Platform, Embedded Edition, application server, at https://glass.sh.dev.java.net.
Sun says it decided to release the code to encourage wider Java adoption, particularly for uses that require open source licensing and development approaches.
The company's decision will result in the release of millions of lines of code to the open source community. JavaSE alone has about 6 million lines, according to Sun.
Raymond said it marks one of the biggest corporate contributions of code to open source development, comparable to Netscape Communications' creation of Mozilla by releasing the Netscape browser code as open source in 1998.
Sun's decision marks a major policy change. The company had closely guarded the Java source code since its initial release in May 1995, citing fears such as users establishing incompatible variations of the technology if Sun didn't control its development.
Sun says that this is still a concern but that the open source release's benefits would outweigh it. Moreover, Sands explained, Sun hopes that people developing alternative approaches resulting from the open source release will make sure they are compatible.
The company has supported open source for some time and probably decided to release Java code to build a strong community for the technology, said Forrester Research senior analyst Michael Goulde.
"As developers build innovative new applications on top of Sun platform technologies such as Java, the value of the platform goes up," said Sands. "Sun is confident that by making the platform more valuable and broadening its adoption, there will be more and more opportunities."
News Briefs written by
Linda Dailey Paulson, a freelance technology writer based in Ventura, California. Contact her at ldpaulson@yahoo.com.
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