#92 Problem with the diode model from the non-linear component library

0.0.17
closed-invalid
nobody
None
5
2013-06-20
2013-02-14
Laurent
No

Hi developers, thank you for the great job.

It seems to me that there is something wrong in the diode model. I ran a simple DC simulation with 0.7 V DC voltage source on the diode terminals and I have obtained the current through the diode Id=0.58 mA (with Is=1e-15 and all other parameters with the default value). The diode equation theoritically gives Id=1.45 mA. (It looks like the thermal voltage has been put eroneously as a dividing factor in the current diode equation).
Could you enlight me?

Laurent

P.S: I'm using the last qucs release running on windows.

Discussion

  • Richard C

    Richard C - 2013-04-30

    Could you attach the schematic demonstrating the issue please?

     
  • Richard C

    Richard C - 2013-04-30

    According to octave the correct current at 300K is:

    >> Is = 1e-15;
    n1 = 1;
    Vd = 0.7;
    
    k = 1.3806488e-23;
    T = 300;
    q = 1.602176565e-19;
    
    Vt = k * T / q;
    
    I = Is * (exp(Vd./(n1*Vt))-1)
    
    I =
    
       5.7476e-04
    

    Note the diode temperature in Qucs is in Celcius, not Kelvin

     
  • Richard C

    Richard C - 2013-04-30

    I'm going to mark this as closed, I think Qucs is correct on this one.

     
  • Richard C

    Richard C - 2013-04-30
    • status: open --> closed-invalid
    • Group: --> v1.0_(example)
     

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