READ NOTES to make it working

What is this red dead end for. And green is also somehow go to nothing. But first whats this red scope?

@hurz the red is the output of the op-amp, the green senses and sets the common voltage of blue and orange through the feedback loop.

"Seems to be the common voltage of blue" you dont know, so were does this circuit comes from when its not your invention?

@hurz I wrote "sets" not "seems", the circuit is clear to me. And by the way of course this is not an invention of mine, it's a super general differential to single ended amplifier.

Still the question from were exactly you made the copy of? Mind or Internet or a book?

@hurz You find everything in the Razavi book, not this specific circuit but all the stages separately (differential, amplification, control). I put things together.

I have my book sources, thanx. Do you made it out of your mind.

@hurz I just put together the stages, nothing creative :)

I can do that too, but I wont do it as you did.

You're going way down again hurz!

Fancynacy, can you please shutup as long you havn't to say something technicaly.

@hurz There are several ways to obtain the same result. One thing to improve is the output dynamic range. If you do your own version then it would be cool comparing.

it would be really cool if hurz made one of his own for comparison.

Ok lets talk direct, I dont like for a very first view to this circuit the following, but maybe @crake you can explain to us what it is for. Anyway, I dont expect to much. @Ermannocit, your first differential amp is modulated by this seconde one in operating current. This does not make sense at all, and is only working with some gain because you set the current bank transistor with a Lambda to 0 !!!!zero!!!! This is more then strange. Lets see how far @crake can explain that?

@hurz The second differential controls the common output of the first one in a opposite way w.r.t. his variations (follow the loop, the feedback is negative). But lambda = 0 is actually the worst case for biasing, it is there to describe the ideal case (no common mode amplification) but it works of course with other values with still a high gain (regarding now the active loads mos).

No, with lambda set, the overall gain drastical goes down, cuz you drive two not perfect current sources, one from top current bank and one from bottom common into the first differential amp. All this you should try to understand if it makes somehow sense, im afraid to say, two modulated current source this way do not make much sense. Simplify the problem and see itself. Normaly if you modulated the common of an differential amp you would like to have something like gain control or even AM. But AM is the last thing you want in an amplifier, cuz AM is sideband and harmonics and this is equal distortion, a thing you try to avoid!!!! Again, analog circuit design as main rule: have a constant current from top or bottom rail and work with it, but dont try to work with another constant source to work against. Try to understand and make a simple model of two current sources working against. You will get the most unstable objects you can imagin. Beginner misstakes.