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I am writing a simple simulator for Mosfet and JFet. The equations governing these involve the important parameter "K". But, the data sheets normally do not provide the value of parameter K. So, I want my program to prompt the user to enter one or two other parameters they CAN find from the data sheet and enter. The program then should be able to compute the value of K using the parameter values the user entered.

(1) What parameter values the program should ask for the case of MOSFET? (2) The same question but for JFET.

Thanks!

Victory
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    see the answer for http://electronics.stackexchange.com/questions/28421/how-to-determine-vth-kn-and-delta-from-nmos-datasheet – efox29 May 13 '15 at 20:25

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K is called the conduction parameter. The simplest way it to get it from the SPICE model that the manufacturer gives for the FET. If the manufacturer doesn't give a SPICE model for a FET... it's usually "no sale" for me...

If you still want to get it from a datasheet... you need to do curve fitting as described in MOS Model Parameter Extraction Techniques: A Comparison by C.G. Cahill, K. McCarthy, W.A. Lane [for instance]. There are some youtube videos showing how to do something like that with just two data points from the graph, but the error you'll get that way is going to be large.

There's a on-line app that seemingly does that (properly) but it's unfortunately in German. However that should give you an idea what you could; essentially ask the use to input several data points from the FET characteristic... the more the better in terms of accuracy.

Fizz
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