Memristor

and memristance

Transcript

1. Memristor
   a memory resistor
   

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2. What is memristance?
   Memristance is a property of an electronic component. If charge flows in
   one direction through a circuit, the resistance of that component of the
   circuit will increase, and if charge flows in the opposite direction in the
   circuit, the resistance will decrease. If the flow of charge is stopped by
   turning off the applied voltage, the component will 'remember' the last
   resistance that it had, and when the flow of charge starts again the
   resistance of the circuit will be what it was when it was last active.
   

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3. Why is memristance important?
   It turns out that memristance is becoming stronger as the feature sizes in
   circuits are getting smaller. At some point as we scale into the realm of
   nanoelectronics, it will be necessary to explicitly take account of
   memristance in our circuit models in order to simulate and design
   electronic circuits properly.
   

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4. Have people seen memristance before?
   Yes, we are aware of over 100
   published papers going back to at
   least the early 1960's in which
   researchers observed and reported
   unusual 'hysteresis' in their current-
   voltage plots of various devices and
   circuits based on many different
   types of materials and structures. In
   retrospect, we can understand that
   those researchers were actually
   seeing memristance, but they were
   apparently not aware of it.
   

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5. What is a memristor?
   An ideal memristor is a passive two-terminal
   electronic device that is built to express only the
   property of memristance (just as a resistor expresses
   resistance and an inductor expresses inductance).
   However, in practice it may be difficult to build a 'pure
   memristor,' since a real device may also have a small
   amount of some other property, such as capacitance
   (just as any real inductor also has resistance).
   

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6. A Memristor Is
   Like A
   Pipe (
   Seriously)
   

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7. What is an analogy for a memristor?
   A common analogy for a resistor is a pipe that carries water. The water itself is
   analogous to electrical charge, the pressure at the input of the pipe is similar to
   voltage, and the rate of flow of the water through the pipe is like electrical current.
   Just as with an electrical resistor, the flow of water through the pipe is faster if the
   pipe is shorter and/or it has a larger diameter. An analogy for a memristor is an
   interesting kind of pipe that expands or shrinks when water flows through it. If
   water flows through the pipe in one direction, the diameter of the pipe increases,
   thus enabling the water to flow faster. If water flows through the pipe in the
   opposite direction, the diameter of the pipe decreases, thus slowing down the
   flow of water. If the water pressure is turned off, the pipe will retain it most recent
   diameter until the water is turned back on. Thus, the pipe does not store water like
   a bucket (or a capacitor) – it remembers how much water flowed through it.
   

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8. Very Fast and High
   Density
   

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9. Two distinct advantages of
   memristors are that moving the
   vacancies between the adjacent
   levels can be done much faster than
   other known switching methods,
   and the cell density approaches that
   of hard disks. Theorized by Leon
   Chua in the early 1970s, and if
   commercially viable, memristors may
   replace flash memory and dynamic
   RAM (DRAM) in the future.
   

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10. What types of applications could memristors have?
    For a type of non-volatile random access
    memory, or NVRAM. Such a memory would
    have very useful properties, in that it would
    not 'forget' the data that it stores when the
    power is turned off. We think that NVRAM
    made with the types of memristor materials
    that are currently being studied by many
    groups around the world could be a strong
    competitor to the flash memory market in
    about five years.
    

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11. It Replaces RAM, Flash And
    Disk
    

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12. What types of applications could memristors have?
    Another interesting application is as
    an 'artificial synapse' in a circuit
    designed for analog computation.
    Prof. Chua himself pointed out the
    connection between the properties
    of his proposed memristor and
    those of a synapse in his earliest
    papers, and he has performed a lot
    of research in the area of neural
    computing. We also think that this
    is a very interesting and potentially
    valuable research direction.
    

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13. It Flattens The CPU Memory Hierarchy Divide
    With memristors you can decide if you
    want some block to be memory, a
    switching network, or logic. Williams
    claims that dynamically changing
    memristors between memory and logic
    operations constitutes a new computing
    paradigm enabling calculations to be
    performed in the same chips where data is
    stored, rather than in a specialized central
    processing unit.
    

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14. 1808 Sir Humphry
    Davy is claimed to have
    performed the first
    experiments showing
    the effects of a
    memristor.
    

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15. 2013 Senior lecturer Dr. Andy Thomas and his colleagues from Bielefeld
    University construct a memristor that is capable of learning. The group
    utilize memristors as key components in a blueprint for an artificial brain.
    The results are presented in the March print edition of the Journal of
    Physics published by the Institute of Physics in London
    

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16. References
    • http://www.hpl.hp.com/news/2008/apr-jun/memristor_faq.html
    • http://en.wikipedia.org/wiki/Memristor
    • http://whatis.techtarget.com/definition/memristor
    • http://www.pcmag.com/encyclopedia_term/0,2542,t=memristor&i=59033,00.asp
    • http://highscalability.com/blog/2010/5/5/how-will-memristors-change-everything.html
    

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