How to caculate the W/L of a MOSFET?

[Mark_]

Hi!

I've come across a very confusing question. I am asked to caculate the W/L ratio from nothing else but a standard Id-VDS plot.
I think we always use W/L together with unCox in MOSFET caculation so how can I take W/L out?

Does anyone have an idea?

 

[Martaine2005]

Hi Mark,
I am useless with math. But that doesn't mean I can't help you.
I am reading a great source about mosfets. It has all your answers and formula, calculations too.
Have a read, or jump to page 4. Here.
When you understand it, perhaps you could explain it to me

Martin

 

[Mark_]

Hi Mark,
I am useless with math. But that doesn't mean I can't help you.
I am reading a great source about mosfets. It has all your answers and formula, calculations too.
Have a read, or jump to page 4. Here.
When you understand it, perhaps you could explain it to me

Martin

well thanks for your reply. I know all those equations but they don't seem helpful since in all those calculations, they use k(W/L) together. so its quite easy to get k(W/L) but since I don't have the k value it seems impossible to get W/L out of those equations.

 

[Martaine2005]

From how I read it, K=ID.
You have the drain current on your graph.

EDIT: I see what you mean. K and W/L are together. I guess I'll have to read it again.

Martin