GAINESVILLE,
Fla. --- Researchers have built a world-record high
frequency chip using a common type of semiconductor,
an advance that could lead to inexpensive systems
for detecting hidden weapons, and chemical and biological
agents.
Engineers
at the University of Florida
and United Micro Electronics
Corp., a Taiwan- based
semiconductor manufacturer,
announced late last week
they had built the 105
gigahertz circuit using
widespread complementary
metal oxide semiconductor, or CMOS, technology – the
same technology found in most of the chips in ubiquitous
personal computers and handheld electronic devices.
The previous record for CMOS circuits was 103 gigahertz,
reported in February of last year, but that circuit
consumed four times more power than the newly announced
circuit and was built using a more advanced technology.
Gigahertz is a measurement of frequency, with one
gigahertz equaling 1 billion cycles per second, or
a wave repeating its motion 1 billion times in one
second.
“It's a demonstration of what these standard technologies
are really capable of, and it also opens up new applications
areas for CMOS,” said Ken O, a UF professor of electrical
and computer engineering.
In
a related development,
Swami Sankaran, a UF doctoral
student in electrical engineering, and O have engineered
a Schottky diode – a device that allows current to
flow in a single direction – to operate at even higher
frequencies of up to 1.5 terahertz, or 1.5 trillion
cycles per second, using the same CMOS technology.
That's the highest operating frequency for any devices
built with the mainstream silicon technology.
Engineers have created such ultrahigh frequency
circuits in the past, but they have been too expensive
for commercial use because of the exotic nature of
the materials involved.
Steve Maas, chief scientist at Applied Wave Research,
a California-based supplier of high-frequency electronics,
said the cost is gradually coming down, but that
high-frequency chips built using the standard CMOS
are a recent and surprising alternative.
“Until recently, no one would have imagined that
CMOS could be capable of operating at such high frequencies,” Maas
said.
“The
next logical step is to
achieve this kind of high-frequency
operation with a process
that is designed for low-cost
fabrication, and this seems
to be what Ken has accomplished.
I don't know what his limitations
are, but it appears to be a very respectable accomplishment.”
The
UF advances suggest it
would be relatively easy
to transform the now experimental devices into inexpensively
manufactured commodities – chips that in the near
future might even reach even higher frequencies.
“Using the diodes we have, it should be possible
to build circuits operating at around 400 gigahertz,” O
said. “Within the next one to two years, the advances
in CMOS could enable fabrication of diodes good enough
to built terahertz circuits with.”
One of the exciting potential applications for such
high frequency devices is chemical and biological
weapons detection, O said. The circuits' high operating
frequency closely matches the vibrating frequency
of the tiny pathogens and chemical bonds that make
such weapons effective, O said.
“Many elements have spectral lines at these frequencies,
so conceivably such circuits could be used to sense
them,” Maas said. “These are not technological pie
in the sky. They are thoroughly practical, technologically,
but cost has always been the main hang up.”
According
to Maas, other applications
for high frequency sensors
include “automotive radar
for crash avoidance, adaptive
cruise control, parking
assistance (and) detection
of obstacles.”
The 105 gigahertz circuit was announced Friday in
a paper presented by O and Changhua Cao, a UF doctoral
student in electrical and computer engineering, at
the 2005 Symposium on VLSI circuits in Kyoto, Japan.
A paper about the Schottky diode will appear in the
July issue of the journal IEEE Electron Device Letters.
Writer:
Aaron Hoover, (352) 392-0186, ahoover@ufl.edu
Source: Ken O, (352) 392-6618, kko@tec.ufl.edu
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