MEMRISTOR

PRESENTED BY

E DHANASEKHAR ( 4th YEAR ECE)

(THE FOURTH FUDAMENTAL PASSIVE ELEMENT)

Four Fundamental Passive Elements

RESISTORCAPACITO

R

INDUCTOR ?..

Symbol -Unit – ohms (Ω)

Definition 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 MemristanceM(q)=dФ

m/dt

• Theory was developed in 1971

by Professor Leon Chau at university of California , Berkeley.

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

•In 2008, R.Stanley Williams developed the practical model

Emergence of memristic theory

Prof. LEON.O.CHAU

Symmetry Relationship

VOLTAGE(V)

CURRENT( i )

CHARGE( q )

FLUX( )

Resistor

Inductor

Memristor

Capacitor

V=R i

q=CV

Ф=𝑴𝒒

Ф= L i

V=dФ/dt i=dq/dt

Working

Pt Pt

. . . .

. . . .

TiO2-x

. . .

. . .

Working cont...• Like silicon, titanium dioxide (TiO2) is a semiconductor , and in its pure state its highly resistive.

• However it can be doped with other elements to make it very conductive.

• In TiO2 , the dopants don’t stay stationary in a high electric field, they tend to drift in the direction of the current.

Cont…Putting a bias voltage across a thin film

of TiO2 semiconductor that has dopant on the one side cause them to move into the pure TiO2 on the other side. And thus lowers the resistance

Running current in the other direction will then push the dopants back into place, increasing the TiO2’s 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.

V-I Characteristics

AdvantagesHard Disk + RAM =MEMRISTOREliminates delaySpeed is inversely proportional to sizeLarge density 1 terabit/cm Analog data storage possibleAct as microprocessor Non volatile memoryUses less energy Compatible with current CMOS interfacesFaster than flash memoryConventional devices use only 0 and 1 ;

memristor can use anything between 0 and 1.

2

ApplicationsArtificial intelligence

Cross bar latches as transistor replacements

Analog computations

Circuits which mimic Neuromorphic and biological systems(learning circuits)

Programmable logic and signal processing

Summing it up…..The memristor will enhance

circuit design in the 21st century as radically as the

transistor changed it in the 20th .

It is believe that it could replace DRAMs by 2014 and maybe Hard

Disk by 2016.

THANK YOU