change in resistance causes unexpected and confused trouble in LTSpice circuit simulation

Discussion in 'Programmer's Corner' started by Emma Pan, May 20, 2016.

  1. Emma Pan

    Thread Starter New Member

    May 20, 2016
    2
    0
    This is totally impossible in theory, but it happens in simulation. Here is the thing:
    Picture1.png The attached image shows the circuit I built and the current curve when R1=0 which is correct (it is the curve that it should be).
    HOWEVER, when R1 changes, the shape of the current curve changes as well, which is QUITE confusing. In my point of view, the current curve will shift when R1 varies but its shape should always be the same.
    Therefore, I cannot understand the second current simulation result. Could you please give me some hints? I am completely confused.
     
  2. crutschow

    Expert

    Mar 14, 2008
    12,993
    3,227
    You're not the only one.
    What is U1?
     
  3. Emma Pan

    Thread Starter New Member

    May 20, 2016
    2
    0
    That is a module I built by myself depend on its IV curve. So you got the same problem? Have you figured it out?
     
  4. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,777
    1,103
    :rolleyes: How can we get the same problem if we don't have the spice model for your mystery module?
    Welcome to AAC!
     
  5. crutschow

    Expert

    Mar 14, 2008
    12,993
    3,227
    No.
    My confusion was about the nature of U1, not that I duplicated your problem (which I can't since I don't have the model for U1).
     
  6. WBahn

    Moderator

    Mar 31, 2012
    17,716
    4,788
    So you don't think that the behavior of the circuit might just depend on what is in this module that you built? And you expect other people to be able to replicate your results without telling them anything about what is in this module that you built?
     
Loading...