The question might sound silly, but I hope experts can guide me on that particular issue. I am struggling for the last few months. I am a beginner in analog circuit design. When I follow a tutorial, I found that by observing a big transistor (MOS)-level circuit, they can say about node voltages, branch current, input and output resistance, and sometimes gain. My question is, without drawing a small-signal model of those circuits, how do people do that? Is this because they already solved many circuits by hand (I mean not using any simulator), and that is why a concept was built? Even when I try to draw a small-signal model for a big circuit I get lost due to the circuit's complexity. What is a good way to approach this kind of circuit?
I added the figure as an example circuit!
Thanks for your time!
Figure reference: https://www.hindawi.com/journals/apec/2014/274795/