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sikhjumn said:I'm confused about the usage of loop gain of Op Amp.
Can anyone tell me the importance of loop gain,e.g. open loop gain&close loop gain?
Thx a lot.
sikhjumn said:Maybe...Are there any practical example for loop gain?
Or any example that the loop gain directly affect the results?
While i search the loop gain through internet, the example always based on mathematics. However, I need more examples baesd on macro views, or any product based on the principle of loop gain.
LvW said:sikhjumn said:Maybe...Are there any practical example for loop gain?
Or any example that the loop gain directly affect the results?
While i search the loop gain through internet, the example always based on mathematics. However, I need more examples baesd on macro views, or any product based on the principle of loop gain.
* One typical example was given in my first answer
* based on the classical feedback scheme, Blacks formula shows the importance of the loop gain L(jw):
Acl=Aol/(1-Aol*F)=Aol/(1-L)
(Notation as in my first answer)
* The sign of L determines if you have positive or negative feedback, and don`t forget: L=L(jw), which means that L decreases (and its phase changes!) with rising frequencies
* Special case: If there is one frequency with |L|=1 (0dB)
and phase of L is 360 deg, the circuit design for amplification will become unstable.
*Recommendation: Try to become familiar with stability criteria; the you will see the importance of loop gain.
fencl said:.............
but, a litter confused me is the simple way of ac analysis for loop gain and phase?.since i've known how to do for Aol and Acl. can you help for this,LvW
ths a lot.
LvW said:fencl said:............
You ask for a way to measure/simulate loop gain?
This subject has been discussed intensively in this forum before.
For example, have a look at "similar topics" at the bottom of this page.
LvW
oh, i've got it ,thx!
LvW said:fencl said:.............
but, a litter confused me is the simple way of ac analysis for loop gain and phase?.since i've known how to do for Aol and Acl. can you help for this,LvW
ths a lot.
You ask for a way to measure/simulate loop gain?
This subject has been discussed intensively in this forum before.
For example, have a look at "similar topics" at the bottom of this page.
LvW