Diode fitting with 5 parameters

I used fsolve function (advised by Mischa Kim) to solve the diode equation and it worked (with small modification on (q/nkT).

fun = @(I) Il - Io * exp((V + I*R)/(n*kT_q)) - (V + I*R)/S - I;

Now I need to do a fitting using the same equation but this time I need Matlab to iterate the values for:

Il , Io, R, n, S,

in order to solve I which will give me the best fit against the experimental I (Iexp) where V is the independent variable. I guess I will need the least square function for that but first how do I ask Matlab to do the iteration and eventually solve the I?

Thank you very much for your help.

Rosemarie

[Rosemarie]

Further to my question above, the 5 parameter (Il , Io, R, n, S,) values will be the same for all Icalc.

Cheers.

Rosemarie

Answer 1

[arushi]

Hi Rosemarie,

To perform a fitting using the diode equation and find the parameters (I_l), (I_o), (R), (n), and (S) that best fit your experimental data, you can use the lsqcurvefit function in MATLAB. This function performs non-linear least squares fitting.

Here's a step-by-step guide to achieve this:

1. Define the diode equation function: Create a function that computes the current (I) given the parameters and the voltage (V).
2. Define the objective function for lsqcurvefit: The objective function should return the difference between the experimental current (I_{\text{exp}}) and the computed current (I).
3. Use lsqcurvefit to find the best-fit parameters: Call the lsqcurvefit function with initial guesses for the parameters.

Hope this helps.