Research News
Boost for Wireless Computing
LEDs Show Promise for Tiny Screens
World's Fastest Chip
Technology Alliance Focuses on Research
IBM Gains Gold in Winter Olympics
Scaling New Storage Heights
Boost for Wireless Computing
The desire to bring the Internet and multimedia to mobile users has sparked
efforts to create wireless technology that can support the high data rates
needed for those services. A group headed by Mehmet Soyuer at IBM Research
has taken a significant step toward that goal. The team has designed and
tested integrated circuits known as voltage control oscillators (VCOs) that
help to generate carrier frequencies in four frequency ranges.
"The VCO is the heartbeat of a wireless
device," explains Modest Oprysko, senior manager of communications
technology at the Thomas J. Watson Research Center.
"It generates the carrier frequency in a wireless system on which the
signal carrying the data is impressed."
The fastest VCO among the latest wireless building blocks developed by the
Watson team generates a band of frequencies around 17.1 gigahertz, the
basis of a new European microwave communications band. The technology also
applies to frequencies at 5 GHz, a band that the U.S. Federal
Communications Commission has dedicated to short-range, high-speed wireless
data communications, as well as frequencies around 9 GHz and 4.4 GHz.
The new VCOs are fully monolithic and contain no external components, such
as inductors and capacitors. Equally important, their fully differential
architecture minimizes noise coupling between digital parts of a highly
integrated chip and a sensitive analog VCO. The added circuitry of such
architecture normally requires higher power levels. However, the silicon
germanium (SiGe) technology that the team used succeeds with minimum
increase in power consumption.
The SiGe circuits that make the new VCOs possible were pioneered by
Watson's Bernie Meyerson. They are at least as fast as the gallium arsenide
(GaAs) circuits normally used for wireless communication. While Soyuer's
team built the SiGe VCOs using the more traditional bipolar devices, they
are actually fabricated in a SiGe
bipolar-complementary-metal-oxide-semiconductor (BiCMOS) technology that
will be fully qualified this year. SiGe BiCMOS permits higher levels of
integration than GaAs.
The Watson team's next step is to integrate the CMOS logic that can combine
the VCO and other circuitry in a device that selects the channels within a
band of frequencies. "You can generate all these functions on a chip," says
Oprysko. In a related development, Soyuer's team has also characterized a
fully monolithic BiCMOS low-noise amplifier for the 5 GHz band. VCOs and
related technology for the 5 GHz band, adds Oprysko, represent "something
you might see in the marketplace in the next year or two."
FYI:
http://www.research.ibm.com/topics/popups/smart/ network/html/vcos.html
LEDs Show Promise for Tiny Screens
As handheld electronic devices become more popular, the need for miniature
high-resolution displays is growing. Among the technologies being explored
are arrays of light-emitting diodes (LEDs) made from crystalline
semiconductor materials. But for that approach to be viable, it must be
possible to grow a suitable semiconductor on an inexpensive substrate -- a
requirement that has proved difficult to meet.
Recently, Supratik Guha and Nestor Bojarczuk, researchers at IBM's Thomas
J. Watson Research Center, have demonstrated a promising route to making
low-cost LEDs based on the semiconductor gallium nitride (GaN). They
selected GaN, says Guha, because "it has an unparalleled combination of
brightness and efficiency when emitting blue and green light, and performs
very well even with imperfections in the crystalline structure." But those
results have been achieved only by growing the material on a substrate of
sapphire or silicon carbide -- materials that are too exotic to be used in
inexpensive displays. Guha's and Bojarczuk's challenge was to find a more
practical substrate.
The two researchers had a hunch GaN could be grown on silicon, one of the
cheapest and most convenient substrates in microelectronics. The hunch
proved accurate, as the pair reported in Applied Physics Letters (January
26, 1998). The resulting LEDs can emit both violet and ultraviolet light.
To obtain a color spectrum, each LED would be coated with an organic color
converter that would absorb the light and re-emit it as a different color.
The devices the researchers have demonstrated are just a start. "They are
very weak in terms of theirlight output, because deposition of the GaN device layers on silicon was
made possible using a different deposition technique from that commonly
used for GaN on sapphire," says Guha. "Much work needs to be done to
optimize the deposition process and increase the devices' efficiency and
electrical characteristics." The pair are also working to solve another
problem: after the GaN has been deposited on the silicon at high
temperatures, the two materials contract at different rates as they cool,
causing the GaN to crack.
If those problems prove solvable -- and Guha feels they will -- arrays of
GaN LEDs could become a strong contender for use in full-color,
high-resolution displays with one-inch-diagonal or smaller screens.
World's Fastest Chip
The IBM austin Research Laboratory made headlines in February when it
unveiled the world's first experimental CMOS microprocessor that can
operate at one billion cycles per second, or a gigahertz -- 1,000
megahertz. To put it into perspective, today's fastest processors typically
operate at 350 MHz or less.
The 15-person design team reached that performance milestone by focusing on
innovations in circuit design and microarchitecture. In doing so, they
showed that speed
improvements could be derived from good design alone rather than from
advances in CMOS technology. "With this demonstration, we believe it is
possible to design 1,000 MHz products," says Austin Lab director and IBM
Fellow Mark Dean.
The 1,000 MHz chip contains one million transistors and was fabricated with
IBM's
current 0.25 micron CMOS 6X technology. Eventually, however, the techniques
from this project will be implemented in microprocessors made with IBM's
recently introduced CMOS copper-chip technology, which should result in
even higher performance.
Technology Alliance Focuses on Research
An alliance between IBM and St. Louis-based bioscience firm Monsanto
Company will facilitate joint research on advanced information technologies
to identify and map the genetic structure of plant groups and human
diseases. Under the agreement, scientists from both companies will use
Teiresias - an algorithm developed by Isidore Rigoutsos and Aris Floratos
at IBM's Thomas J. Watson Research Center - to speed up the discovery of
hidden patterns in Monsanto's databases of DNA and proteins. "Using
Teiresias, we expect to make discoveries that wouldn't be possible using
existing tools," says Patrick Fortune, Monsanto's chief information
officer. The anticipated result: faster development of new products.
The collaborative agreement contains two other components. An IBM/Monsanto
Solution Center will help companies to implement Enterprise Resource
Planning systems. These business management software systems integrate
corporate financial data with other functions, to provide comprehensive
overviews of operations. And under a 10-year outsourcing agreement, IBM
Global Systems will provide Monsanto with data center management, help-desk
operations and support for 8,000 desktop systems.
IBM Gains Gold in Winter Olympics
Athletes weren't alone in setting world records at the recently concluded
Winter Olympic Games in Nagano, Japan. The official Web site of the Games,
powered by IBM, took almost 650 million hits. That figure -- unprecedented
for a sports site -- more than tripled the number at the 1996 Summer
Olympics in Atlanta. On the 14th day of the winter event, the site
registered traffic at a world-record rate of 103,429 hits per minute.
"Technology did win gold in Nagano," said François Carrard, director
general of the International Olympic Committee. "I want to offer special
emphasis and thanks to IBM."
Much of that success stems from upgrades of the 1996 technology, carried
out by a team at IBM Research. "We wanted to devise a scheme to present
information in a much more appealing way to users," explains Paul Dantzig, manager of Olympic Internet
application development at the Thomas J. Watson Research Center. "That
required building the system in a different way." For example, he explains,
"new cache management and trigger monitor technology allowed us to update
information 60,000 times in a day, which we couldn't have conceived of
doing in Atlanta."
The net result was far more detailed levels of information than available
previously. Web surfers could check results, news, photographs and athlete
quotes not only by sport but also by event, country and individual athlete.
And every page on the Web site was updated within one minute of any
development that related to it. The audience obviously approved. "Thousands
of responses have told us how wonderful the Web site was," says Dantzig. *
Scaling New Storage Heights
A close collaboration between scientists at IBM's Almaden Research Center
and its Storage Systems Division has achieved a world-record data-storage
density of 11.6 gigabits per square inch on a hard-disk drive. The
achievement, equivalent to packing the information contained in more than
725,000 double-spaced typewritten pages on each square inch of disk, more
than doubles the old storage record, set by IBM just last year.
The advance stemmed from several factors. A key element is the use of IBM's
new giant magnetoresistive (GMR) head, a radically new magnetic-field
sensor design that can detect smaller bits, or magnetized regions, on the
disk surface. Also critical for achieving the record are the
narrower-track, thin-film inductive write head, a less noisy cobalt-alloy
magnetic media material, and improved coding and channel electronics.
In addition, nearly all of the operating parameters are tightened another
notch. For example, as data densities increase, the read/write sensors on
the head must fly closer to the disk surface than ever before, to ensure
that the signal from the smaller bits remains strong. In the laboratory
demonstration, the 1.25-millimeter-long "picoslider" containing the head
flies only 10 nanometers above the disk surface, which spins at 4,000 to
10,000 revolutions a minute. "It's hard to imagine flying so close to such
a rapidly moving surface," says Currie Munce, Almaden's director of storage
systems and technology. "If you scaled the slider up to a 180-foot-long
airliner, for example, it would be like flying around the world once a
minute with the airliner's tail only a half-millimeter above the ground."
Some of the technologies that contributed to the record will appear in
products this year. IBM is already shipping disk drives with GMR heads --
an industry first -- and products with this record data density will become
available for mobile computers within three years, according to Robert
Scranton, vice president for technology at the Storage Systems Division.
Desktop drives at this density could hold as much as 72 gigabytes of data,
4.5 times the current maximum desktop-drive capacity.
REMARKABLE RATE OF IMPROVEMENT
This latest laboratory demonstration highlights the remarkable rate of
improvement in data storage in recent years. Since 1991, when IBM
introduced the industry's first magnetoresistive sensor, the data density
of hard disk drives has doubled every 18 months -- an annual increase of 60
percent, double the average 30 percent improvement in each of the 35 years
before 1991. Since the cost of a disk drive of equivalent complexity
remains about the same, customers are getting much more for their money
every year.
Such improvements are occurring hand-in-hand with customers' growing desire
to access and get value from their expanding stores of online data. "With
the emergence of e-business, network computing and the World Wide Web,
businesses and individuals alike want to sort and sift through huge amounts
of online information so they can extract the knowledge they need," Munce
says.. "Our new technologies that help create bigger, faster and cheaper hard
drives are central to the success of this new information environment."
Higher densities are also expected to enable new types of disk drives and
applications. A tiny disk
drive that would plug into a standard flash-memory socket, for example,
could enable digital cameras to store large numbers of high-resolution
photos
affordably and to expand greatly the data-storage
capacity of personal digital assistants or other handheld computers. And on
the desktop, Munce says,
capacious disk drives might permit new applications such as video email.
