amplifiers: how can i sum two amplifiers with diferent properties

Thread Starter

naoficoemcasa

Joined Oct 6, 2018
6
heelo,
i have this exercise where i'm supost to sum 2 amplifiers with diferent characteristics, but i'm having a dificult time on how to.amp.PNG
 

danadak

Joined Mar 10, 2018
4,057
Are you supposed to do a discrete design inside dashed amp block, or
use opamps or.....a little more description would help.

Homework I gather ?

Regards, Dana.
 

Thread Starter

naoficoemcasa

Joined Oct 6, 2018
6
thanks for replying , this exercise has 3 questions. The first one is : Determine the values for Avo, Ais, Rmo and Gms of the equivalent amplifier (shown in broken lines, in the figure).
 

danadak

Joined Mar 10, 2018
4,057
If you look at what you know

1) You are given Vin, Vout, so you know composite Av
2) Therefore you know Av of first stage
3) You know output load and current, so calc Gm second stage
4) Knowing that you can calc composite Gm

I do not know what Ais or Rmo terms mean ?

Regards, Dana.
 

The Electrician

Joined Oct 9, 2007
2,778
If you look at what you know

1) You are given Vin, Vout, so you know composite Av
2) Therefore you know Av of first stage
3) You know output load and current, so calc Gm second stage
4) Knowing that you can calc composite Gm

I do not know what Ais or Rmo terms mean ?

Regards, Dana.
There's another thread with similar parameters: https://forum.allaboutcircuits.com/threads/help-for-gain-parameters-for-quadrupoles.152778/

I think that the second subscripts ("s" and "o") may stand for "short" and "open". That is, Avo means "open circuit voltage gain" and Ais means "short circuit current gain". Could Gms be "short circuit transconductance"? Rmo may be an output resistance, but I don't know what the "m" represents.

naoficoemcasa, can you provide an explanation of these terms?
 
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