op amp differentiator in LTSpice

Discussion in 'Homework Help' started by boablahuj, Apr 7, 2016.

  1. boablahuj

    Thread Starter New Member

    Mar 3, 2016
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    Hello. I've designed differentiator scheme in LTSpice and for some reason it's not working properly. Values are okay I think, I would love to know what am I doing wrong, since I'm trying to get this to work for few hours now. Phase is completly wrong on the output and I'm not sure if capacitor C1 is needed. My scheme:
    [​IMG]
    This yellow box is op amp, 1 - non-inverting input, 2 - inverting input, 3 and 4 +/- power supply and 5 - output.
     
  2. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
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    hi,
    It would help if you posted your LTS asc file.
    E
     
  3. boablahuj

    Thread Starter New Member

    Mar 3, 2016
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    Sure, I've attached my scheme.
     
  4. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,508
    380
    hi,
    Where did you get the TL061 model from.?
    The pin outs are non standard.

    I have used a TL071 as I do not have the LTS TL061 model.
    E
     
  5. Jony130

    AAC Fanatic!

    Feb 17, 2009
    3,963
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    What output did you expect to see ? At 10Hz 3.6nF capacitor will have Xc = 4.4MΩ ( Megohms)
     
  6. boablahuj

    Thread Starter New Member

    Mar 3, 2016
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    I imported PSPice model and used it few times already, every time it worked perfectly.
    And that's the output I want to see:
    [​IMG]
    i have fixed parameters: Uinput = 4V, Uoutput = 2, frequency = 5kHz. I could choose R, so I went with 10k, and then calculated C = 2.5nF and R1 << 1273 ohms, so I choose 100 ohms for now (No values form E24 series for now).
     
  7. Bordodynov

    Active Member

    May 20, 2015
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    See

    Diff.png
     
  8. boablahuj

    Thread Starter New Member

    Mar 3, 2016
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    Results of your simulation are similiar to mine, so it turns out my sim is okay. I was worried because of the phase shift, but my teacher said it's done properly. Thanks a lot for all feedback!
     
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