Introduction to Memristor

1. MEMRISTOR
BY SABARINATH S

2. Fundamental Elements Of Electronics
•Resistors, Capacitors and Inductors are the
fundamental elements of electronics.
•Relations connecting pairs of four
fundamental circuit variables via. current I,
voltage v, charge q, and magnetic flux Φ.
•Resistors are used to relate current to
voltage, capacitors to relate voltage to charge
and inductors to relate current to magnetic
flux
•The relation between the charge and the
flux was unknown.

3. Memristor
• The fourth fundamental element.
• A semiconductor whose resistance varies as a function of magnetic flux (Φm) and
charge (q) .
• Non-linear two terminal electric component.
• Characterized by memristance.
MEMRISTOR EQUIVALENT CIRCUIT ELECTRIC SYMBOL

4. • Memristance is a property of an Electrical component that describes the variation in
resistance of a component with flow of charge.
M(q) = dΦm/dq
• Unit: Ohms
• Retains its resistance level even after power has been shut down or last resistance it
had before shut off.

5. History
• Memristor was first theorized by Professor Leon Chua in the early 1970’s at
University of California, Berkely.
• He developed mathematical equations to represent memristor.
• In the beginning of 2006, the group of researchers headed by R Stanley Williams at
HP labs, developed a practical model.
• It was a simple model of binary switch based on the coupled movement of both
charge dopants and electrons in the semiconductor .
• They found that the defining equations for switch were identical to Chau’s
mathematical definition.

6. Chau's theory
• Each Memristor is characterized by its memristance
function describing rate of change of flux with charge.
M(q) = dΦm/dq
• From Faraday’s law of induction that the magnetic flux is
simply the time integral of voltage and charge is time
integral of current.
M(q) = dΦm/dt * dt/dq = V/I
• Thus, we can say that the memristance is simply charge-
dependent resistance.
V(t) = M(q(t)) * I(t)
Professor Leon Chua

7. Construction of Memristor
The construction of memristor can be done in the following steps:
• Take an element that has resistive properties. Here we are considering the case of
titanium dioxide.
• The material is placed between two electrodes made of platinum.
• The internal section is divided into two parts. One side is doped titanium oxide and
other side is left undoped. The doped section is a variable one.

8. Working
• 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.

9. Analogous System
•The analogous system of a memristor is perfectly explained assuming that memristor
behaves like a pipe whose diameter varies according to amount and direction of
current passing through it.
• The pipe which is switched on again, remembers what current has flowed through it.

10. Current V/S Voltage Characteristics
• In ordinary resistors there is a
linear relationship between
current and voltage so that a
graph comparing current and
voltage results in a straight
line.
• However, for Memristors a
similar graph is a little more
complicated.
• No phase shift introduced
between current and voltage
at zero crossing.

11. Types Of Memristor
• Based on the design and material used for construction memristor can be classified
into two types. They are;

12. Applications
• Memristors are used in digital memory, flash
memory, logic circuits, biological and neuromorphic
systems.
• Memristors are used in neutral networks as well as
analog electronics.
• These are applicable for analogic filter applications
• Remote sensing & Low-power applications.
• Memristors are used in Programmable Logic & Signal
Processing

13. Advantages
The advantages of Memristor are;
•high storage.
•capability to memorize a flow of
charge.
•don’t use power when they are
inactive.
•provides better resiliency and
reliability.
• capable of restoring both hard
drives as well as DRAM.
Disadvantages
The disadvantages of Memristor are;
•not available commercially.
•The speed of Existing versions
simply at 1/10th than DRAM.
•performance & speed will not
match transistors and DRAM​
•Since all data on the computer
becomes non-volatile, rebooting will
not solve any issues as it often times
can with DRAM

14. Summary
The memristor will enhance circuit design in 21 st century radically
as transistors in the 20 th century.

15. THANK YOU