Small signal analysis of MOSFET. Calculating Gain

Status
Not open for further replies.

Hauzron

Newbie level 1
Joined
Jun 2, 2015
Messages
1
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
8
I can do DC analysis and draw the small signal equivalent circuit just fine. I generally have trouble calculating gain. I'm having trouble understanding the answer to this question.

This is the question. Question 4.36: "]

This is my working. I hope it is clear:


According to the solution manual this is the wrong answer. The correct answer is `Av = Vo / Vo + 1`:

I don't understand. Vi is in parallel with Vsg therefore it Vi must equal Vsg right? Where did I make a mistake?
 
Last edited by a moderator:

Vi has not to be equal to Vgs because coupling is capacitive and Vi signal will be on the Vgs so the input signal at the gate of the MOS will be;

Vgs+Vi=Vgs+Vi*cos(wt+Theta)
 

Status
Not open for further replies.

Similar threads

Cookies are required to use this site. You must accept them to continue using the site. Learn more…