wjx197733
Member level 2
Hi, all:
I find there have a difference in the books writed by Razavi and the book writed by you. Both these two book discuss Miller compensation, but there have a difference that puzzles me.
In the book writed by Allen, the equation 6.2-54 explain that the second pole P2 increase Gm multiply Rds, where Rds is the channel resister of M8.
But in the book writed by Razavi, the equation 10.43 explain that the second pole wp2 increase Gm multiply Rs, where Rs is the output resister of the first stage OP.
I do not know which answer is right, so I write a email to Allen, there is his email to me: "There is no difference in the equations. In our book rds/3 is correct if you assume that all rds's are approximately equal. In Razavi's book, he just lumps all the resistance at the gate of M1 into Rs. Note that he has idealized M2 and I2. In his book Rs will be approximately rds divided by some factor depending on the
respective values of each transistors rds.
Phil Allen"
I don't know his meaning, I think somebody can discuss with me.
I find there have a difference in the books writed by Razavi and the book writed by you. Both these two book discuss Miller compensation, but there have a difference that puzzles me.
In the book writed by Allen, the equation 6.2-54 explain that the second pole P2 increase Gm multiply Rds, where Rds is the channel resister of M8.
But in the book writed by Razavi, the equation 10.43 explain that the second pole wp2 increase Gm multiply Rs, where Rs is the output resister of the first stage OP.
I do not know which answer is right, so I write a email to Allen, there is his email to me: "There is no difference in the equations. In our book rds/3 is correct if you assume that all rds's are approximately equal. In Razavi's book, he just lumps all the resistance at the gate of M1 into Rs. Note that he has idealized M2 and I2. In his book Rs will be approximately rds divided by some factor depending on the
respective values of each transistors rds.
Phil Allen"
I don't know his meaning, I think somebody can discuss with me.