I want to know how we can obtain turn-on voltage graphically from I-V characteristics of PN junction.
Are you refering to cut-in voltage? In that case, the tangent to the curve at higher bias(>>3 KT/q, < 0.7 V) is extended to intercept the x axis. The x-intercept is the cut-in voltage.
Hello Ananth sir
Is there any specific point where tangent need to be drawn or any point for the range you have mentioned (>>3 KT/q, < 0.7 V) , i will be able to get cut-in voltage correctly.
Dear Shashikant,
welcome,
This answer may come late. To determine the cut in voltage of the pn-diode you make a linear plot of the I-V curve in the current range of interest.
Then, it appears as broken line with two pieces; one horizontal pieca and one inclined piece with the twp pieces are the best linear fit to the real I-V curve. The intersection point of the two pieces will be the cut-in point.
So, it is practical to find different values of the cut in voltage depending on the fitted current range. So, one has to give the cut in voltage with its valid current range.
For more information please see the link: Book Electronic Devices
Best wishes
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