Regarding the Op-amp compensation...

[malli_1729]

Hi!

i am weak in basics regarding the analog design....i don't have any practical experiance.....
due to that i am not getting the interpretation or proper usage of the concepts which i am learning in theory. in those topics opamp compensation is one.

Dominent Pole compensation,Lead/Lag compensation and some of others...
in theory i am knowing what each one is.....equations are also difficult to understand.......but interpretation i can't able to get....and how can i see how can each compensation modifies the closed loop TF of an op-amp....

is there any nice material regarding this ....

Help in this regard is very grateful to me.....

thanks

 

[LvW]

....and how can i see how can each compensation modifies the closed loop TF of an op-amp....
is there any nice material regarding this ....
Help in this regard is very grateful to me.....
thanks

* More interesting and more important is the open loop TF of an opamp
* There are a lot of application notes from the solid-state manufacturers (TI, Analog Devices,...) describing compensation in detail.

 

[malli_1729]

Thnx for the reply.

u told most important is "OpenLoop TF" .
But as we will use Opamp in most of the applications in closed loop form, and in one of the application notes from TI, i have seen that compensation is done to make opamp stable with feedback.
is it OK that we always have to concentrate on Openloop TF ????

Regarding the materials:

i have seen the application notes from TI they are explaining using equations and bode plots.
They will show open loop TF and it's Bode plot first , then after applying the some 'X' compensation TF and Loop gain are modified in bode plot like this....

i need to see them atleast in simulation....then i can understand how internals will work..

 

[LvW]

u told most important is "OpenLoop TF" .
But as we will use Opamp in most of the applications in closed loop form, and in one of the application notes from TI, i have seen that compensation is done to make opamp stable with feedback.
is it OK that we always have to concentrate on Openloop TF ????


The open loop response must be modified with the aim to stabilize the amplifier when feedback is applied. In order to see, if it is necessary and how the compensation network must be designed, you need the open loop BODE diagram because the stabilization criteria (Nyquist) are based on the open-loop response


i have seen the application notes from TI they are explaining using equations and bode plots.
They will show open loop TF and it's Bode plot first , then after applying the some 'X' compensation TF and Loop gain are modified in bode plot like this....
i need to see them atleast in simulation....then i can understand how internals will work..


If you like to understand the principles of compensation, first you have to learn something about the cause of instability of a system with feedback (Nyquist criterion).

 

[malli_1729]

Thnx boss...

i will read "cause of instability of a system with feedback (Nyquist criterion)" first...
then i will come back....

once again thnx for support....