News: negative capacitance discovered

Discussion in 'General Electronics Chat' started by vpoko, Feb 4, 2015.

  1. vpoko

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  2. joeyd999

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    Sounds like the capacitor equivalent of a gunn diode.
     
  3. Alec_t

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    Ahh, a flux capacitor. Just what I need for the time machine I built in 2081 :).
     
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  4. Reloadron

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    Jan 15, 2015
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    You too? I need one for my matter transfer device so I can beam my ex-wife into the center of a concrete and brick wall. :)

    Ron
     
  5. GopherT

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    Careful, alec_T could use his flux capacitor to blow you back to when she wasn't your ex-wife.
     
  6. Reloadron

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    Ya know, I never thought of that. Alec, get it working I need to go back to 1975, June of '75 would be cool. Thank you Gopher for pointing that out.

    Ron
     
  7. Alec_t

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    It is working, ...... in 2081. Unfortunately it won't have a reverse gear until 2317 :(.
     
  8. MachineHum

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    Yes.
     
  9. WBahn

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    It sounds like the article isn't making a distinction between large-signal and small-signal behavior, but what they do describe would be consistent with an incremental negative capacitance riding on top of an overall large-signal positive capacitance. Depending on how much hysteresis the phenomenon exhibits, it could well have some interesting and useful properties.
     
  10. ErnieM

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    I started on a time machine once. It was going very well until I was startled to see I had tapped myself on the shoulder and told myself "this will not end well."

    Nuff for me. No more playing around with the time continium.
     
  11. joeyd999

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    You could've at least given yourself a stock or Superbowl tip.

    Or, at a minimum, "Whatever you do, don't marry that girl!"
     
  12. GopherT

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    Everything else was survivable or reversible except further work on the time machine. Therefore, I think the most critical message was passed through the continuum.
     
  13. joeyd999

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    That would be "discontinuum", no?
     
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  14. #12

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    I can't imagine how to make this useful, but those eggheads will probably find a dozen applications in a month.
     
  15. GopherT

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    You are right in your literal phrase but wrong in the way I perceive what you said. The way I read your comment "...those eggheads will probably find a dozen applications in month" implies that those are real and useful applications. I think they will ride out their careers writing papers, writing research proposals and promoting their discovery. I doubt we will ever see any useful implementation of negative capacitance.

    By the way, if capacitance causes voltage to trail current, would negative capacitance cause the reverse? Oh, wait, that is just inductance. So, what is negative capacitance exactly?

    Kidding aside, it appears to me that they found a way to measure the capacitance while a crystal phase transition occurs - rapidly changing the charge density. Phase (or crystal lattice) commonly changes with temperature (e.g. iron at 910 C). Rapid light pulse has shown change - I don't have a reference handy. I would not be surprised if a rapid electrical pulse can do the same.
     
  16. WBahn

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    My guess is that it's a voltage-induced phase transformation.

    Just as the negative resistance region of tunnel diodes have useful applications, I suspect that the negative capacitance region of these materials will have useful applications.
     
  17. nsaspook

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    They might as advanced Meta-Materials.
    http://www.e3s-center.org/pubs/106/PEB2012_7_DSievenpiper_Webfinal.pdf
     
  18. Alec_t

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    It will make a brilliant high voltage generator (if you believe Spice!) ;). Check this sim of the cap charging from a 1V supply :-
    NegativeCapacitance.gif
     
  19. WBahn

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    The problem with the sim is that it is modeling the large-signal capacitance as being negative. That's not the case -- it's the small signal capacitance over a limited operating region that is negative.

    Just as with the negative resistance region of a tunnel diode, if the large-signal resistance was negative then the diode would be producing power, but because it's the incremental resistance that is negative you don't have that.
     
  20. Alec_t

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    Sorry, I forgot the [joke][/joke] tags ;)
     
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