How to Break the loop of a negative-feedback circuit??

[ZengLei]

Hi all
As all we know that there're 4 kinds of negative-feedback~~~forms.
I can distinguish them,but i don't know how to break the loop of a feedback circuit
which is in different feedback forms respectively~~

So,Pls teachl me how to break the close-loop of a feedback circuit in diff feedback forms,and also how to calculate the feedback factors~~

Thanks~~~~~~

 

[salerno]

Read the book
Analysis and Design of Analog Integrated Circuits (4th Edition) by Paul R. Gray, Paul J. Hurst, Stephen H. Lewis, and Robert G. Meyer
for details