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Nonlinear Implicit Fitting diode curve problem

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Drone0

Korea
1 Posts

Posted - 03/21/2017 : 11:38:11 AM

Origin Ver. and Service Release (Select Help-->About Origin): originpro 64-bit 9.3.1
Operating System: win 10 64 bit

Hi all,

I have some problem for implicit fitting, I tried to figure out parameter from nonideal IV curves using fitting ftn.

this is nonideal diode function. so I use this for fitting. like "f=Is*(exp((q*(V-I*Rs))/(k*T))-1)+((V-I*Rs)/Rsh)-I"
T : temperature
Is : saturation current
Rs : series resistance
Rsh : shunt resistance
q : electron charge
I : current
V : bias voltage

however It doesn't work and shows "Fit did not converge - reason unknown." messege and linear graph.
So then I tried to refer to similar circumstance "fitting diodic curve"
http://www.originlab.com/forum/topic.asp?TOPIC_ID=20339

but still no affect.

I tried procesure as follow

I chose implicit because diode function is "y=x~~y" form.

then I click fit.
however

error messege and linear form graph which doesn't look like original diodic curve.
(I also use initialize parameters, fit until converged. but no affect)

is it problem of software or just wrong input setting?

Yoo

yuki_wu

896 Posts

Posted - 03/22/2017 : 01:06:09 AM

Hi,
Please take a look at this quick help and then try to find the reason why you are not getting a good fit:
http://www.originlab.com/doc/Quick-Help/BadFitResult-Solution

If the problem isn’t gone, please sending your FDF file and your data to the tech support for more help. You can find the contact information here: http://www.originlab.com/index.aspx?go=COMPANY/ContactUS

Regards,
Yuki
OriginLab

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