Download Presentation Memristorx

By
ADITYA NAGARAJ MASKERI
1DS07EE006
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Introduction and History of Memristor.
Fundamental Circuit Elements
The 4th New Fundamental Element
Delay in Discovery
Properties and Working
Analogous System
Potential Applications
Conclusion
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Currently known fundamental passive elements –
Resistors, Capacitors & Inductors.
Does a 4th passive element exist..?
Leon O. Chua formulated Memristor theory in his
paper “Memristor-The Missing Circuit Element” in
1971.
Team of scientists headed by R. Stanley Williams
of Hewlett Packard, realized Memristor made of
Titanium Dioxide in 2008.
Memristors are passive two terminal circuit
elements.
Behaves like a nonlinear resistor with memory.
Resistor
 Resistor is a 2 terminal
electronic component that
produces a voltage across
its terminals that is
proportional to electric
current through it in
accordance with ohm’s
law.
 Ohm’s Law: “ Voltage
(V) across a resistor is
proportional to the
current (I) through it
where constant of
proportionality is the
resistance (R)”.
 V=IR
 SI unit is ohm (Ω).
Symbol
Capacitor
Capacitor is a passive electronic
component consisting of a pair of
conductors separated by a
dielectric.
When a voltage potential
difference exists between the
conductors, and electric field is
present in the dielectric.
This electric field produced stores
energy.
Current- voltage relation:
Where,
C = Capacitance
i(t) = Current
v(t) = Voltage
q(t) = Charge = C*v(t)
SI unit of Capacitance is farad (F).
Symbol
Inductor
Inductor is a passive circuit
element that can store energy
in a magnetic field created by
the current passing through
it.
Inductor is a conducting
wire shaped as a coil.
When current flows
through a coil, it sets up a
magnetic field inside the coil.
Current-Voltage relation:
Where,
L = Inductance.
SI unit of Inductance is
henry (H).
Symbol
RELATION WITH THE
FUNDAMENTAL ELEMENTS:
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Resistor – Voltage and
Current
Inductor – Current and
Flux
Capacitor – Voltage and
Charge
No relation between
Flux and Charge.
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Leon Chua first theorized
the existence of
Memristors.
In 2008, R. Stanley
Williams & team at HP
Labs developed a TiO2
Memristor.
The memristance relates
the Flux and the Charge.
No combination of
existing fundamental
circuit elements can
emulate the effect of
Memristor.
Memristor
An atomic force microscope image of a simple circuit with 17 memristors lined up
in a row. Each memristor has a bottom wire that contacts one side of the device
and a top wire that contacts the opposite side. The devices act as 'memory
resistors', with the resistance of each device depending on the amount of charge
that has moved through each one. The wires in this image are 50 nm wide, or
about 150 atoms in total width.
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Definition:
“The Memristor is formally
defined as a two-terminal
element in which the magnetic
flux Φm between the terminals
is a function of the amount of
electric charge q that has
passed through the device.”
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Symbol:
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Equation:
Memristance is a property of
an electronic component to
retain its resistance level
even after power had been
shut down or lets it
remember (or recall) the last
resistance it had before being
shut off.
Unit of measurement is ohm
(Ω).
•Information can be written into the material as the resistance state in a
few nanoseconds using few pico-joules of energy.
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Current v/s Voltage
Characteristics
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Hysteresis model of
Resistance v/s
Voltage
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The effect depends on
atomic scale
movements.
Detectable only under
nano-scale.
M is 1 million times
larger are nano-scale
than at micrometer scale
due to factor 1/D2.
Where,
D = Thickness of
semiconductor film
sandwiched between
two metal contacts
Memristance as a function of charge:
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Semiconductor used is
TiO2 .
Two layers, one pure and
another doped.
Voltage applied with
negative potential to
doped region yields high
resistance.
Voltage applied with
positive potential to
doped region yields low
resistance.
Device remembers its
previous state even after
power is switched off.
Black
Circles – Memristor
VA – VD - Inputs
V1, V2 – Transistor Power Supply Voltages
Memristor behaves like a pipe whose diameter varies according to the amount and
direction of current passing through it.
The diameter of pipe remains same when the current is switched off, until it is switched
on again.
The pipe, when the current is switched on again, remembers what current has flowed
through it.
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Nano-Scale devices.
Replacement of Flash Memory.
Replacement for D-RAM.
Brain-like Systems.
Self-Learning Systems.
“ Memristors are so significant that it would be
mandatory to re-write the existing Electronics
Engineering textbooks”.
- Leon Chua & R. Stanley Williams