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Opamp compensation-buffer

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akbarza

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hi
in below picture( from saxena thesis-Indirect Feedback Compensation Techniques for Multi-Stage Operational Amplifiers- page 21) i have two questin:
according to Razavi book, in source follower ,the impedance seen from output(here source ) is small and impedance seen from input of source-follower is large. in this thesis, author says that feed-forward current must be omitted, so source-follower is used to omit feed-forward current.
is the picture correct? namely in pic , should not node-2 connect to source of the source-follower and c-c connect to gate of transistor ?
can compensation capacitor(c_c) be in right side of source follower? if yes,are the transfer function and results changed?

thanks
saxen21.PNG
 

It's just right as shown in the schematic. You seem to misunderstand the principle of miller feedback compensation, injecting a current into node 1 controlled by the node 2 voltage. Due to the non-zero impedance of node 2, the basic miller compensation scheme also involves feedforward from node 1 to node 2. The shown buffer is a Methode to eliminate it.
 

thanks FvM
CAN you explain principle of miller feedback compensation?
i know only that for an impedance z with gain A in across it, the we split this z to two impedance as z/(1-A) and z/(1-1/A).
can you explain how feed-forward current is omitted?
thanks
 

Read the chapter 6 and 10.6 in B.Razavi-Design of CMOS Integrated circuits. Every answer is there, these are well explained in the literature.
 
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