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I modeled two different PID controllers with Laplace and with the same control parameters in LTspice, but the results show me the same behavior of the two PID controllers in .AC and different behavior in .TRAN. As in the picture.

My question would be:

  • Why do I get the same behavior in the .AC, but not in the .TRAN?
  • How does LTspice mathematically integrate Laplace in the .TRAN?
  • Where does this go wrong?

enter image description here

Arsenal
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ast30277
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    See if [this](https://electronics.stackexchange.com/q/254602/95619) helps. – a concerned citizen Jul 02 '20 at 14:24
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    [Earlier closed question](https://electronics.stackexchange.com/questions/508432/how-ltspice-integrates-a-laplace-function-of-a-pid-controller-in-the-time-domain) – Andy aka Jul 02 '20 at 14:25
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    I've seen you tried to format your question in the editor, but the rendering happens a bit differently as you see it in the editor, so you need two `return` to create a new line in the rendered result for example and a certain indent to start a list. While writing the question, you have a preview, so have a look at how your question will look like when you post it and you can fix formatting beforehand. Helps the readers a lot. – Arsenal Jul 02 '20 at 14:41
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    @ast302277 please post your spice netlist – Voltage Spike Jul 02 '20 at 16:13
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    You also have [this](https://electronics.stackexchange.com/q/508528/95619) question and in the [comments](https://electronics.stackexchange.com/questions/508528/how-to-simulate-a-laplace-function-of-a-pid-controller-in-the-time-domain-with-l#comment1302071_508528) I already said "*Without seeing the subcircuit one can only guess*". Please focus on one question, and one alone, and make that question such that an answer can be given, not guessed. That means you should make sure that it has enough details. Help us help you. Posting a picture of a generic transfer function does not help. – a concerned citizen Jul 02 '20 at 19:40
  • Also, why do you simulate from nHz to kHz, and what source does that `PULSE` belong to, or is it just some text? – a concerned citizen Jul 02 '20 at 19:42
  • Thank you all for your quick help. I apologize for the late reply. I had no internet connection all day – ast30277 Jul 03 '20 at 20:20

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