 
Newest
version of UC Berkeley computer model, used widely by semiconductor
industry, will help with design of future speedy electronics
24
Mar 2000
By
Robert Sanders, Public Affairs
BERKELEY
-- When it comes to computer chip design, the world is turning
increasingly to the University of California, Berkeley, for
expertise.
In
the past three years, more and more chip manufacturers have
adopted a computer model created at UC Berkeley to design and
simulate the operation of new integrated circuits - computer
chips - before going to the expense of fabricating them. Called
BSIM, for Berkeley Short-channel IGFET Model, it can model the
operation of single transistors or millions linked in an integrated
circuit, like a computer processor.
Now,
to pave the way for future advanced electronics, the UC Berkeley
researchers have developed a new version of the computer model,
BSIM4. Released today (Friday, March 24), it is provided free
to the semiconductor industry.
"It
paves the way for engineers to design computer chips with blinding
speed, and wireless electronics that communicate at higher frequencies,"
said Chenming Hu, the lead developer of the model and TSMC Distinguished
Professor of Microelectronics at UC Berkeley.
"If
you have a hundred, a thousand or a million transistors to simulate
in a circuit design, you want a very efficient and accurate
transistor model," said Ralph K. Cavin, vice-president
for research operations at the Semiconductor Research Corporation,
a non-profit industry-supported consortium that funds some $30
million in research at 65 universities each year. "BSIM
has shown itself to be such a model."
"It
has become the de facto industry standard," added Lawrence
Arledge, a Texas Instruments engineer on loan to SRC as program
manager for integrated circuits and systems and the computer-aided
design testing program.
BSIM4
is likely to be adopted as the design standard by all of the
companies that have adopted the previous version, BSIM3, plus
many others. Significantly, BSIM3 has been adopted as a standard
model by the world's three largest foundries - companies that
fabricate chips for design firms. This means that most of the
electronic circuits in the world will be designed using this
computer model.
"When
the foundries adopt a standard model, it's like laying down
the law - four hundred design companies will design chips using
the Berkeley model," Hu said.
"BSIM
is the lingua franca between design houses and the foundry,"
Cavin said. "It's how they talk with one another; they
express themselves in BSIM models."
BSIM3
was recommended three years ago by the Compact Model Council,
an organization that standardizes compact models across the
semiconductor industry, after it evaluated various CMOS circuit
models. By then already broadly adopted, BSIM3 has since taken
off. The council members include Intel, IBM, Motorola, TI, AMD,
Hitachi, Philips and some 15 other large companies.
"The
semiconductor industry depends heavily on simulation using BSIM3v3,
and we believe that BSIM4 will have a similar acceptance,"
said Britt Brooks, chair of the Compact Model Council. "The
phase - in time may not be as quick as BSIM3v3, since BSIM3v3
still works well for many leading edge designs today. However,
we believe that BSIM4 will allow leading edge design simulation
for the next two to three technology generations."
Brooks
noted that UC Berkeley contacted the council before embarking
on development of BSIM4, allowing major semiconductor manufacturers
to suggest areas that needed research.
"Because
the leading semiconductor companies have been directly involved
with the project, we believe that many of the previous problems
encountered with model development and adoption have been solved,"
Brooks said.
Cavin
said that the new version represents a significant improvement
over BSIM3.
"The
new version has several new features, including for the first
time the ability to design wireless products and the capability
to deal with circuits miniaturized beyond 0.1 microns,"
Hu said. "BSIM4 can design higher frequency, larger chips
with more functions, and ultimately deliver cheaper products
to the consumer."
BSIM
is essentially a four-page-long mathematical equation that simulates
the operation of a transistor. The new model, BSIM4, introduces
original physics models of transistor operation in the time
scale of one percent of a trillionth of a second. In such a
short time, light travels a mere thousandth of an inch. BSIM4
also introduces a new model for the noise in transistors that
has puzzled engineers for decades. With this accurate noise
model, circuits can be designed to provide clearer transmissions
via cellular phones, for example.
BSIM4
was developed by Hu, research engineer Weidong Liu and graduate
students Xiaodong Jin and Mark Cao.
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