How can I check if the Millers theorem is applicable?

[Hackson]

Miller's theorem

How can I gurantee Miller's theorem is applicable. Razavi's book just states that it is not always applicable. So, when is it applicable and when is it not?

 

[nxing]

Miller's theorem

If there is only one path for signal, it's not applicable.

 

[opamp741]

Re: Miller's theorem

That was just one case, according to razavi there cud many situations when miller theorem can not be used.

 

[Hackson]

Re: Miller's theorem

It seems to me that every theorem is the form :
A=> B

so if B is that the impedance can be decomposed into two impedances connected to the ground, then what is A?

 

[alphi]

Re: Miller's theorem

find a mosfet basic article ,you can find it theory.
IR,Fairchild all have such application note.

 

[batdin]

Re: Miller's theorem

Maybe the limitation is the phase-frequiency response of the amp.
If the phase is not 180 deg,e.g. at HF,the formula is not exact.

 

[Hackson]

Re: Miller's theorem

Hey buddies,

I've just found out that Miller theorem can be applied only when the impedance Z in interest doesn't cause any change to the gain between X and Y. That's why razavi says that if Z is not the main signal path, Miller's theorem can be applied.