Design procedure for two stage opam(gm/id)

[cranky_here]

Design procedure for two stage opam

Hey,
I see many posts on design of two stage opam.But honestly,I don't know where to begin and everything is seeming vague.I wrote the equations(transfer function)of a two stage opam from the equivalent circuit.Now i don't understand a few basic things
>>Is the equivalent circuit representing two opams a combination of a few mosfets or two single mosfet?
>>What do the parameters gm,id etc. mean..transconductance for the first opam or the first mosfet.

Please direct me on how to go about understanding this.

:idea:8O


thanks !!

 

[pacman326]

Increasing gm of driving transistor of a stage increases gain, decreases bandwidth
Increasing Id increases bandwidth, decreases gain.

You should also be careful if using a common source stage as second after a differential pair. The miller effect can absolutely destroy bandwidth.

But there are a million considerations outside that when you get into noise and whatnot. What are you looking for more specifically? I may also not be completely correct, as these are things I have picked up in my continued education as an undergrad.

 

[cranky_here]

Hey pacman326,
Thanks a lot for the reply.
What am looking for?8O:shock:
>>The question put forward to me is design a two stage amplifier give some specification say 60 degree PM,100 gain and so on
>>I want to simulate this is in spice(i know how to use spice but don't know how to go about this)

Thanks
Cheers,
cranky

 

[cranky_here]

Hey
Could somebody please help

 

[erikl]

Hey
Could somebody please help

No hope, I fear, before you provide any more info.

If you don't bother about parameters like power consumption or noise, you'd at least utter an idea of the required bandwidth.