thank you for replying. Yes, indeed, it is from chapter 9 Razavi book. i am having trouble understanding how to get the gain quation Av = gm1gm2ro2ro1gm3ro3. The book did not explain how to get that equation. And I dont really know how to figure it out. Do I have to draw a small signal model for this circuit? But then I want to learn how to fugure out the gain from a design point of view. I mean, I cant draw a small signal model for every circuit that i want to analyze. I will never be a good designer if I do it that way. I want to be able to figure out the approximate gain of a particular circuit by just looking at it. But how?
Added after 20 minutes:
I would also like to know how to figure out the min and max Vout...
The min Vout is Vod2+Vgs3. But how to get that equation?