There is this question from the midterm review examen (the one that is provided as an example and include answers) but I'm totally lost with a simple question and answer is the problem 1 in page 28 about a MOSFET in the triode region, howdo they manage to obtain such Small Signal Equivalent, with theresistance 1/B

NOTE : This is not a graded problem, its on the example guide and is provided with answer so is legal, I just want to understand how they managed that so far it's my only caveat in that guide thanks in advance and plenty success and good luck to you all soon to take the midterm :

Question

There is this question from the midterm review examen (the one that is provided as an example and include answers) but I'm totally lost with a simple question and answer is the problem 1 in page 28 about a MOSFET in the triode region, howdo they manage to obtain such Small Signal Equivalent, with theresistance 1/B 

NOTE : This is not a graded problem, its on the example guide and is provided with answer so is legal, I just want to understand how they managed that so far it's my only caveat in that guide thanks in advance and plenty success and good luck to you all soon to take the midterm :

venomghost · Answer

Here the problem and the answer provided how could you to obtain such graphic?

anonymous · Answer

$$i _{ds}=Av _{gs}+Bv _{ds}$$What made sense to me was that $$v _{gs}$$was a controlling input voltage, hence a voltage controlled current source. But the $$v _{ds}$$was an output voltage. To get a current from a voltage you have to divide it by a resistance. Since our factor B is multiplying our voltage, our resistor is the reciprocal of B.