# MOSFET: How can I find conduction parameter and transconductance based on graphs?

So I have my graphs (below) with various MOSFET characteristics. I don't know device dimensions or geometry, therefore I can't solve for the 2 directly with an equation. Otherwise I would just do that.

That being said, any ideas on how to solve for transconductance and the conduction parameter based on my graphs?

Conduction parameter:     Transconductance is a volt to amp ratio of the change in input voltage to change in output current when in saturation (constant current) mode: - Transconductance at the area shown above is approximately (9-7)volts/4 mA = ~500. At lower gate voltages, transconductance is more because the change in $$\I_D\$$ is less.

I'm unsure what you mean by "conduction parameter". Maybe you can link to some reference material.

• What I mean by conduction parameter is solving for k in the equation 'k = [W*u(n)*C(ox)] / 2L'. There should be a way to do so, but I'm still trying to figure that out. – Austin Brown Nov 24 '18 at 13:25
• Also, if I am just wanting to find transconductance at say 10Vg, how do you do this? At first I thought maybe take the slope of the 10Vg curve in the saturation region. What do you think? – Austin Brown Nov 24 '18 at 13:38
• Difficult to just pinpoint a value because you have to assume Vg varies about 10 volts in order to produce a signal current in the drain. – Andy aka Nov 24 '18 at 15:19
• I don't follow. Do you have any suggestions on finding this value? I feel it shouldn't be that difficult with the given data used to produce the graphs and the graphs themselves, I haven't found a good method yet. :/ – Austin Brown Nov 24 '18 at 15:41
• Finding this value? Use the graphical method I adopted and recognise that it generally increases as Vg goes down. Or use other data in the data sheet for the device or setup a test. – Andy aka Nov 24 '18 at 15:45