Berkeley Science Review 20 - Smart Circuits
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Transcript of Berkeley Science Review 20 - Smart Circuits
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8/6/2019 Berkeley Science Review 20 - Smart Circuits
1/212 Berkeley Science Review Spring 2011
Smart circuits
Making electronics thatremember
Electrical engineering is on the cusp of a
breakthroughone that will al low engineers
to create circuits that drastically increasethe speed of processing, use far less power
than modern computers, and even mimic
the kind of computations carried out by the
human brain. This shift comes in the form
of the memristor, a long-theorized but only
recently constructed electrical component
that stores information about its past activity
and uses this information to influence its
behavior. First theorized nearly 40 years ago,
and finally built by Hewlett-Packard Labs
in 2008, it promises to redefine the abilities
and applications of computers of the future.While memristors have only recently
been constructed, they have existed in theo-
retical electronics for many years. Leon Chua,
a longstanding member of the Department
of Electrical Engineering and Computer
Sciences at UC Berkeley, laid out the original
theory in 1971. In his paper, Chua addressed
a hole that existed in our knowledge of elec-
trical engineering.
The world of electronics is largely built
around devices that carry out interactions
between the basic variables in any circuit:
charge, resistance, voltage, and flux. For
example, a capacitor creates a voltage by
maintaining an imbalance of electrons (or
charge) on either side of a gap. At the time
of the theorys publication, there was a clearexplanation for how a real-world device
could connect each combination of these
elements but one: charge and flux.
Chua theorized a new circuit element
to carry out the missing interaction. This
element would behave very similarly to a
resistor, but with one key difference: the
amount that it impeded the flow of electricity
would depend on the current that had already
passed through. In essence, this electrical
element would have a memory, combining
information about the past with its input inthe present. For this reason, Chua dubbed
this new element the memristor.
Though it made a splash in theoreti-
cal electronics, it would be nearly 40 years
until the memristor would be realized in the
laboratory. Up to that point, Chuas depiction
of the properties of memristors had been
likened to the elusive Higgs boson of theo-
retical physics: a particle that exists in theory
but has not yet been observed. Then, in 2008,
HP Labs announced that they had created a
nano-scale circuit that showed exactly the
same properties that Chua had theorized.
Memristors were real.
Although memristors have yet to
be successfully integrated into standard
electronics, the ability to engineer circuitswith memristors is improving rapidly, and
hybrid memristor/traditional computers are
expected to make their first appearance in
consumer technology in the next few years.
Your next computer could have memristors
that allow for faster booting and processing.
These early successes bode well for a para-
digm shift in the future of electronics. While
most modern computers perform calcula-
tions using dynamic random access memory
(DRAM) that must be wiped clean every time
a computer loses power, a new memristor-equipped computer could remember the
state from when it was last turned off and
boot up nearly instantaneously.
Memristors could also decrease comput-
ers power consumption, which has increased
exponentially as demands on processors
continue to rise. Currently, this power
consumption poses a significant challenge
to increasing the complexity and power of
processing chips. Memristors, however, con-
sume relatively little power because storing
memory within small units, rather than ina separate system, allows designers to use
fewer and shorter wires, and thus less power.
Memristor systems bring data close to com-
putation, much as biological systems do,
explains Massimiliano Versace, a researcher
at Boston University who is using memristors
to study, and possibly create, models that are
inspired by human cognition.
The potential to create highly intercon-
nected systems that are eerily similar to the
way our own brains are structured is one of
the most exciting potential applications formemristors. For many years, scientists have
tried to model human cognition, but have
often fallen short due to the limitations of
our current hardware. Such systems are built
with specific locations for computations (cen-
tral processing units, or CPUs), short-term
memory (dynamic random-access memory,
or DRAM), and long-term memory (the hard
BriefsMemristors
An image of an array of memristors formed at the
intersection of crossed microscopic wires. Each is
approximately 150 atoms wide.
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8/6/2019 Berkeley Science Review 20 - Smart Circuits
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