Memristor

Welcome Seminar on

MEMRISTOR

19 Sept. 2009

MEMRISTOR

Memristor

Memory Resistor+

Memristor

Defination of Memristor A memristor is a semiconductor whose

resistance varies as a function of flux and current. This allows it to “remember” what has passed through the circuit.

Characterized by Memristance

Memristance Memristance is simply charge-dependent

resistance. V(t) = M(q(t))*I(t)

Unit - ohm (Ω)

Symbol

Emergence Of Memristic TheoryTheory was developed in 1971 by

Professor Leon Chua at University of California, Berkeley.

Found while exploring symmetry between the three fundamental passive linear circuit elements

In 2006, R.Stanley Williams developed practical model.

Fundamental Circuit Variables

Voltage, V (V) – work done required to bring charge from ∞ to a Electric field.

Current, I (A) – flow of electric chargeFlux, Φ(W) – rate of flow through an

areaCharge, Q (C) – energy per electron

Fundamental Relationships

Current is the derivative of Charge

Q= ∫I dt

Voltage is the derivative of Flux

V= ∫ dΦ/dt

Symmetry Of Relationships

Voltage (V)

Current(i)

Charge (q)

Flux (Φ)

3 Fundamental Passive Linear Elements

Capacitor,C (F)

Resistor,R (Ω)

Inductor,L (H)

CAPACITORS

q = C v

Symmetry Of Relationships

Voltage (V)

Current(i)

Charge (q)

Flux (Φ)

q=CvCapacitors q=CvCapacitorsCapacitors

RESISTORS

Ohm’s Lawv = R i

Symmetry Of Relationships

Voltage (V)

Current(i)

Charge (q)

Flux (Φ)

Resistors v=Ri

Capacitors q=CvCapacitors

INDUCTORS

Φ = L i

Symmetry Of Relationships

Voltage (V)

Current(i)

Charge (q)

Flux (Φ)

Φ = Li Inductors

??

v=dΦ/dt i=dq/dt

Resistors v=Ri

q=CvCapacitors

Symmetry Of Relationships

MemristorsΦ=Mq

Voltage (V)

Current(i)

Charge (q)

Flux (Φ)

Φ = Li Inductors

v=dΦ/dt i=dq/dt

Resistors v=Ri

q=CvCapacitors

Relationship With Other VariablesΦ = M q

dΦ/dt = M(q) dq/dt

V(t) = M(q) I

P = I² M(q)

Property Of Memristor Retain its resistance level even after

power had been shut down

Remember (or recall) the last resistance it had, before being shut off.

Memristic State Found when researching ways to overcome

nano-scale manufacturing issues. Memristivity has an inverse square relationship

with thickness of the material, so smaller = better!

Nonvolatile state can be accomplished by memristors because their state is encoded by impedance (physically), not by voltage.

WORKING

PT PTTiOv(2-x)

TiO2

3 nm

2 nm

OxidizedReduced

(-)ve (+)ve

Applied voltage makes the oxygen vacancies (+ve) to shift towards the –ve voltage.

WORKINGShift between the layers in

permanent in nature.It exist even after the voltage has

been removed.Causes the permanent change in

resistance

Analogy Of Memristor

A RESISTOR WITH MEMORY BEHAVES LIKE A PIPE

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.

Why So Late ??? As its effect depends on atomic-scale

movements, it only poped up on the nanoscale of William’s devices.

Benefits Of Memristor TechnologyWould allow for a quicker boot up since

information is not lost when the device is turned off.

Hard Disk + Ram = MEMRISTOR

Benefits Of Memristor TechnologyUses less energy and produces less heat.Eliminates the need to write computer

programs that replicate small parts of the brain.

Benefits Of Memristor Technology Compatible with current CMOS interfaces Power Consumption

As non-volatile memory, memristors do not consume power when idle.

Behaviour 3 Memristors to make a NAND gate 27 NAND gates to make a Memristor

Benefits Of Memristor TechnologyCreating a Analog Computer that

works much faster than Digital ones.Provides greater resiliency and reliability

when power is interrupted in data centers.

Density allows for more information to be stored.

What Sets Memristor Apart ?? Conventional devices use only 0 and 1;

Memristor can use anything between 0 and 1.

Faster than Flash memory. Allow digital cameras to take pictures with

no delay inbetween Innovating nanotechnology due to the fact

that it performs better the smaller it becomes.

Future Technological SignificanceBeing implemented to do neural

computing. (post office, banks).Pattern recognition and learning.Crossbar latches to replace

transistors.

Future Technological SignificanceSmaller, lower power consumption

SSDs.New forms signal processing and

control systems.Memristors can be used to do digital

logic using implication instead of NAND.

Not Perfect Yet ! Though hundreds of thousands of

memristor semiconductors have already been built, there is still much more to be perfected.

Needs more defect engineering. No design standards (rules). Fair endurance (overlookable e.g..

Transistors

Questions ???