Memristor:The missing circuit element

We are very much aware of the three basic elements of electric circuits i.e. the resistors,the inductors and the capacitors.In september 1971, Leon Chua published a paper named as “Memristor:The missing circuit element”.In his argument he first considered the general equation of the capacitor
i = C(dV/dt)………………..(1)
but according to him when the capacitance varies with time eg. C = (5+3sint) then it is found that eqn (1) doesn’t give the correct value of current for a given applied voltage. If we integrate eqn (1) we’ll get
q(t)= C(t)V(t) …………………(2)
and we would say its just the same as eqn(1) but its not when its not linear or in other words when the capacitor is time varying. So when we put C= 5+3sint in eqn(2), we get
q(t)=(5+3sint)V(t) if we differentiate this we’ll get

i = (5+3sint)dV(t)/dt + (3cost)V(t) so this is the missing term if we solve it by eqn(1). Now we can write for inductor as well.

V = L(di/dt)
if we integrate we’ll get Φ =Li or rather Φ(t)=L(t)i(t)
Now, we have four items

* Current(i)
* Voltage(V)
* Charge(q) i.e integral of i
* Flux(Φ) i.e integral of V

So there are relations between each two relevant terms but what was missing was a relation between flux(Φ) and charge(q).So Leon in his paper formulated

Φ(t) = M(t)q(t)

if we differentiate we can conclude that M(t) has the unit of Ohms so he named it as ‘memristor’. As it can store memory in them unlike usual resisters.So this is the history of memristors.

In May 2008, Hewlett Packard made it possible and made memristor a reality.
So can you imagine lighting a bulb and then pulling out its plug from the source and the bulb still glowing.Think about memristors!!!

The defect with memristor is that it is not lossless hence it will dissipate energy and so the above scenario cannot be reached but there are concepts of “Memory capacitors” and “Memory Inductors” which are proven to be lossless devices which i’ll talk in the next post.With them coming the above scenario would be nothing less than a reality!