MEMRISTOR pediain.com

Known Three fundamental passive circuit elements: Resistor, Inductor, Capacitor. pediain.com

Does a fourth fundamental element exist? v Resistor dv=Rdi Capacitor dq=Cdv q i ? Inductor dF =Ldi Memristor dF =Mdq Leon Chua proposed the existence of memristor in 1971 In 2008 a team lead by Stanley Williams created the first memristor φ pediain.com

What is a MEMRISTOR Memristor is really a MEMory ResISTOR Memristor can be defined as a two terminal device which shows the relation between magnetic flux and charge memristor symbol pediain.com

Memristor Theory Or Or pediain.com

Memristor and Resistor The way resistor has resistance , memristor has memristance. Same unit –ohm. Memristance can be switched to different states. Memristor has non linear v-i plot. pediain.com

Memristor features resistance depends on magnitude, polarity and time application of voltage. Save its electronic state when current is turned off. “Remember” how much current has passed through it. pediain.com

Physical analogy for a memristor Resistor is analogous to a pipe of fixed diameter through which water is flowing Water(charge q), input pressure(voltage v), rate of flow of water(current i). Resitance depends on diameter. Memristor is analogous to a special kind of pipe that expands or shrinks when water flows through it. The pipe is directive in nature. If water pressure is turned off, pipe will retain its most recent diameter, until water is turned back on. pediain.com

Physical analogy for a memristor Pipe Charge Water Conductance Cross sectional area Potential Pressure When water flows in one direction the diameter increases (resistance decreases) When water flows in opposite direction the diameter decreases (resistance increases) pediain.com

Why memristor a fundamental element Can not be duplicated by R,C,L. Peculiar behaviour- carries memory of past. Duplication requires alot of transistors and capacitors. pediain.com

V-I characteristics Resistor-energy dissipated Capacitor-store energy in electric field Inductor-store energy in magnetic field MEMRISTOR Store Information pediain.com

Course of development First predicted by Leon Chua in 1971 when he was a rising professor at The university of california. His paper “Memristor-The missing circuit element”. was published in the IEEE Transactions on circuit theory. First solid state version in 2008 by a research team led by R.Stanley Williams of HP Labs. Reported in a prestigious science journel, NATURE publishes “The missing memristor found”. Built from Titanium dioxide with cross bar structure. pediain.com

Construction of TiO2 memristor Pt TiO2-x TiO2 Initially there are two layers, one slightly depleted of Oxygen atoms, other non-depleted layer. The depleted layer has much lower resistance than the non-depleted layer. Equivalent circuit pediain.com

Working of TiO2 memristor Tio2-x Ron Roff Tio2 pediain.com

1 Working as a switch Positive direction-close the switch. Off state (high resistance) On state (low resistance) 1 Positive direction-close the switch. Negative direction-open the switch. pediain.com

Memristor structure Crossbar array An atomic force microscope image of a simple circuit with 17 memristors lined up in a row.  Each memristor has a bottom wire that contacts one side of the device and a top wire that contacts the opposite side.  The devices act as 'memory resistors', with the resistance of each device depending on the amount of charge that has moved through each one. The wires in this image are 50 nm wide, or about 150 atoms in total width. pediain.com

Crossbar array Array of perpendicular wires. Anywhere two perpendicular wires cross, there is a switch connecting them. To connect any horizontal wire to a vertical wire the switch sandwiched between those two wires must be closed. A crossbar array -a storage system. pediain.com

Types of memristors 1. Molecular and Ionic Thin Film Memristive Systems Titanium dioxide memristors Polymeric (ionic) memristors 2. Spin Based and Magnetic memristive systems Spintronic Memristors/ Spin Torque Transfer (STT) uses magnetization to alter the spin direction of electrons in two different sections of a device. magnetization state of the device is changed by current electron spin through spin torque induced magnetization motion. pediain.com

Materials used Oxides such as WO3,Ir2O3,ZrO2 and RhO2. Other variations such as TiO ,CuO ,NiO, ZrO. Perovskite materials. Molecular and polymer materials- rotaxane pediain.com

Manufacturing No need of expensive retooling. Nanoimprint lithography. pediain.com

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It’s time to stop shrinking. A typical processor chip in a laptop contains over a billion transistors. In which transistors are 1000 times smaller than the diameter of a human hair. It’s time to stop shrinking. Further miniaturisation of transistors yields unpredictable results. The emphasis in electronics design will have to shift to devices that are not just increasingly infinitesimal but increasingly capable. Memristor is the perfect example of such a device. pediain.com

Requires a power source to retain a data state. Transistor Memristor 3-terminal switching device with an input electrode (e.g. source), an output electrode (e.g. drain), and a control electrode (e.g. gate). Requires a power source to retain a data state. Stores data by electron charge. Scalable by reducing the lateral length and width dimensions between the input and output electrodes. Capable of performing analog or digital electronic functions depending on applied bias voltages. Fabrication requires optical lithography. 2-terminal device with one of the electrodes acting either as a control electrode or a source electrode depending on the voltage magnitude. Does not require a power source to retain a data state. Stores data by resistance state. Scalable by reducing the thickness of the memristor materials. Capable of performing analog or digital electronic functions depending on particular material used for memristor. Fabrication by potentially cheaper mass production techniques such as nanoimprint lithography. pediain.com

Benefits Reliability when power is interrupted. Great data density. Less expensive. Operating outside of 0s and 1s. By changing current,behaviour can be changed. Do not consume power when idle. May replace transistors in ICs and has the potential to open door to a brand new type of electronics. pediain.com

Future pediain.com

Applications As a switch. As a non volatile memory. Booting free computers. Can perform logic operations. In artificial neural networks. pediain.com

Nonvolatile memories The resistance-saving property makes memristors very appealing for use in computer memory & freezing property prevents unintentional loss of memory due to a power failure. pediain.com

Booting free computers Instant-On Computers Memristors would potentially be able to remove lengthy reboot since it freezes when power off. pediain.com

Logic/computing Memristors appear particularly important to the areas of reconfigurable computing architectures such as FPGAs in which the arrangement between arrays of basic logic gates can be altered by reprogramming the wiring interconnections. Memristors may be ideal to improve the integration density and reconfigurability of such systems. pediain.com

In artificial neural networks pediain.com

Synapse=memristor pediain.com

Hence artificial Brain pediain.com

Big companies involved in research pediain.com

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Conclusion The rich hysteretic v-i characteristics detected in many thin film devices can now be understood as memristive behaviour. It takes a lot of transistors and capacitors to do the job of a single memristor. No combination of R,L,C circuit could duplicate the memristance. So the memristor qualifies as a fundamental circuit element. May replace transistors in Ics and has the potential to open door to a brand new type of electronics. pediain.com

Conclusion It is sure that Memristor is going to revolutionaries the 21st century as radically as the transistor in the 20th century But Memristor will have to wait a few years ,like transistor which had to wait almost a decade after it’s invention for its popular applications. Finally as Leon O Chua mentioned It’s time to rewrite all the EE textbooks” pediain.com

References "Memristor—The Missing Circuit Element", IEEE Transactions on Circuit Theory by Leon O Chua (1971) "Memristive Devices and Systems" in the Proceedings of the IEEE by Leon Chua and his student Sung Mo Kang (1976) "The missing memristor found" Nature (may2008) IEEE Spectrum - The Mysterious Memristor, by Sally Adee (may 2008) IEEE Spectrum - How We Found the Missing Memristor, by R. Stanley Williams (dec 2008) pediain.com

Web links en.wikipedia.org/wiki/Memristor www.hpl.hp.com/news/2008/apr-jun/memristor.html www.memristor.org www.newscientist.com/article/mg20327151.600-memristor-minds-the-future-of-artificial-intelligence.html www.youtube.com/ucberkley http://blogs.howstuffworks.com/2009/07/24/ how-does-a-memristor-work/ www.spectrum.ieee.org pediain.com

Video links Memristor and Memristive Systems Symposium (4 parts) total of 5 hours 6-Minute Memristor Guide Memristors The Missing Link(3:38) pediain.com

THANK YOU pediain.com