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Basics of memristor
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- 2. INTRODUCTION • Memristor isa concatenation of “memory resistors”. • Fourth passive circuit element. • Maintain a relationship between the time integrals of current and voltage across a two terminal element. • Nonlinear resistor with memory. MEMRISTOR SYMBOL
- 3. HISTORY • Theory wasdeveloped in 1971 by Professor Leon Chua at University of California, Berkeley. • In 2008, a team at HP Labs under R.Stanley Williams claimed to have found Chua's missing memristor based on an analysis of a thin film of titanium dioxide. • In March 2012, a team of researchers from HRL Laboratories and the University of Michigan announced the first functioning memristor array built on a CMOS chip.
- 4. MEMRISTOR • Its resistance(dV/dI) depends on the charge that had flowed through the circuit. • When current flows in one direction the resistance increases, in contrast when the current flows in opposite direction the resistance decreases. • 2 terminal device relates magnetic flux and charge.
- 5. CONSTRUCTION • Platinum actsas the electrodes. • Two layers of Titanium dioxide is in between the electrode. • One of which has a slight depletion of oxygen atoms.
- 6. • The oxygenvacancies acts as charge carriers. • When positive voltage is applied , the holes are repelled . • The length of depleted layer is increased, which increases the resistance. • When negative voltage is applied , resistance decreases as length decreases.
- 7. PROPERTY • Retain itsresistance level even after the power supply is turned off or shut down. • Remembers or recalls the last resistance value that it had , before shut down. • When the current is stopped the resistance retains the value that it had earlier. • It means memristor “REMEMBERS” the current that had last flowed through it.
- 8. THEORY • It definesrelationship between magnetic flux linkage Φm(t) and the amount of electric charge that has flowed, q(t) f(Φm (t),q(t)) = 0 • The variable Φm ("magnetic flux linkage") is generalized from the circuit characteristic of an inductor. • It does not represent a magnetic field here. • The symbol Φm may be regarded as the integral of voltage over time.
- 9. MEMRISTANCE • In therelationship between Φm and q, the derivative of one with respect to the other depends on the value of one or the other • So each memristor is characterized by its memristance function describing the charge-dependent rate of change of flux with charge. M(q) = dΦm dq Substituting the flux as the time integral of the voltage, and charge as the time integral of current M(q(t)) = 𝒅Φm/𝒅𝒕 𝒅𝒒/𝒅𝒕 = V(t) I(t)
- 10. APPLICATIONS • Used indigital memory, logic circuits, biological and neuromorphic systems. • Used in computer technology as well as digital memory • Used in neural networks as well as analog electronics. • These are applicable for analogic filter applications • Remote sensing & Low-power applications. • Used in Programmable Logic & Signal Processing. • They have their own ability for storing analog and digital data in an easy as well as power efficient method
- 11. ADVANTAGES OF MEMRISTOR •Has properties which can not be duplicated by the other circuit elements (resistors, capacitors, and inductors) • Capable of replacing both DRAM and hard drives • Smaller than transistors while generating less heat • Works better as it gets smaller which is the opposite of transistors • Devices storing 100 gigabytes in a square centimeter have been created using memristors. • Requires less voltage (and thus less overall power required)
- 12. DISADVANTAGES OF MEMRISTOR •Not currently commercially available • Current versions only at 1/10th the speed of DRAM • Could be learned but can also learn the wrong patterns in the beginning. • Suspected by some that the performance and speed will never match DRAM and transistors.
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