memristor

Welcome Seminar on

MEMRISTOR

19 Sept. 2009

By:- Mangal Das

Himanshu Ramchandani

MEMRISTOR

Memristor

Memory Resistor+

Memristor

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 Memristance

Memristance Memristance is simply charge-dependent

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

Unit - ohm (Ω)

Symbol

Emergence Of Memristic Theory Theory 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 charge Flux, Φ(W) – rate of flow through an

area Charge, Q (C) – energy per electron

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

Resistors v=Ri

q=CvCapacitors

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)

Φ = Li Inductors

The Missing Link

?

v=dΦ/dt i=dq/dt

Resistors v=Ri

q=CvCapacitors

Symmetry Of Relationships

Φ=Mq

Voltage (V)

Current(i)

Charge (q)

Flux (Φ)

Φ = Li Inductors

Memristor

v=dΦ/dt i=dq/dt

Resistors v=Ri

q=CvCapacitors

Relationship With Other Variables Φ = 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.

Output =F(present value + previous value of resistance.)

Pinched Hysteresis Loop

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

* When I=0 , Then V becomes 0

The applied voltage (blue) and resulting current (green) as a function of time t for a typical memristor.

Pinched Hysteresis Loop

* For memristors, the Previous graph is reprented as a PINCHED HYSTERESIS LOOP

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 cathode.

WORKING Shift 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.

Delay In Discovery

As its effect depends on atomic-scale movements, it only poped up on the nanoscale of William’s devices.

Benefits Of Memristor Technology Would allow for a quicker boot up

since information is not lost when the device is turned off.

Hard Disk + RAM = MEMRISTOR

Benefits Of Memristor Technology

Uses less energy and produces less heat. Smaller, lower power consumption SSDs. 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 Technology Creating 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.

Distinct Behaviour Of Memristor 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 in between Innovating nanotechnology due to the fact

that it performs better the smaller it becomes.

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)

Thank You

QUESTIONS