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� A memristor is a semiconductor whoseresistance varies as a function of flux andcurrent. This allows it to ³remember´ what
has passed through the circuit.� This technology may replace transistors,
N AND flash memory, and even digital
logic as we know it.� Emerging technology in working prototypephase.
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� Physics behind memristic theory
� Chemistry behind memristic design
� Future technologies and potential of memrisitic systems
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� Theory developed in 1971 by Professor
Leon Chua of U. C. Berkeley
� Found while exploring symmetry betweenthe three fundamental passive linear
circuit elements.
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� Voltage, V (V) ± potential difference
between two points.
� Current, I ( A) ± flow of electric charge� Flux, (W) ± rate of flow through an area
� Charge, Q (C) ± energy per electron
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� Current is the derivative of Charge
� Voltage is the derivative of Flux
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V I
Q
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� Capacitor,C (F)
� Resistor,R ()
� Inductor,L (H)
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V I
Q
Capacitors q=Cv
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� Ohm¶s
Law
� v = R i
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� = L i
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V I
Q
Capacitors q=Cv
Resistors
v=Ri
Inductors=Li
v=d/dt i=dq/dt
?
?
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Fundamental Memrisitive System Theorem:
� Any two-terminal device which exhibits a
pinched hysteresis loop in the voltage vs.current plane, thereby relating charge and
flux.
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� = M q
� d/dt = M(q) dq/dt
� V(t) = M(q) I� P = I V
� P = I² M(q)
� P = I² R
Symbol of a menristor
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V I
Q
Capacitors q=Cv
Resistors
v=Ri
Inductors=Li
v=d/dt i=dq/dt
=Mq
Memristors
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� The number of
transistors that
can be placed
inexpensively on
an integrated
circuit has
doubledapproximately
every two years.By Moore¶s law
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� O Vacancy Drift Model for TiOv(2-x) Switch (Developedby R. Stanley Williams of HP Labs, 2008)
PT PTTiOv(2-x)
TiO2
3 nm
2 nm
Oxidized
Reduced
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� The HP device is composed of a thin (50 nm) titaniumdioxide film between two 5 nm thick electrodes, one Ti,
the other Pt. Initially, there are two layers to the titanium
dioxide film, one of which has a slight depletion of
oxygen atoms. The oxygen vacancies act as charge
carriers, meaning that the depleted layer has a muchlower resistance than the non-depleted layer. When an
electric field is applied, the oxygen vacancies drift (see
Fast ion conductor ), changing the boundary between the
high-resistance and low-resistance layers. Thus the
resistance of the film as a whole is dependent on how
much charge has been passed through it in a particular
direction, which is reversible by changing the direction of
current.[
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� Have great data density.
� 100 GBs of memory made from memristors on
same area of 16 GBs of flash memory.
� Creating a Computer that never has toboot up.
� Does not lose information when turned off.
� Has the capacity to remember the chargethat flows through it at a given point in
time.
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� Compatible with current CMOS interfaces
� Power Consumption
± As non-volatile memory, memristors do not consume
power when idle.
� Size
± 3 Memristors to make a N AND gate
± 27 N AND gates to make a Memristor
± CMOS N AND Area 36 x (FP)² = .3µ² @ 45 nm
± Memristor N AND Area 3 x (FP)² = .05µ² @ 45 nm
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� Though hundreds of thousands of memristor
semiconductors have already been built, there is
still much more to be perfected.
� Dissipates heat when being written to or read.
� Needs more defect engineering.
� No design standards (rules).
� Fair endurance (overlookable e.g.. Transistors).
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� Hope to one day have a computer thatprocesses information in the same way asthe human brain.
� Could lead to the replacement of thetransistor.
� Used in common devices for unbelievable
storage.� Appliances that ³learn´ from experiences.
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