input signal and cmfb

[shanmei]

when the input signal frequency increase, it seems that the cmfb can not control the output DC voltage , how to slove the problem? thank you

 

[sunking]

the pdf is not clear.
maybe you can check the driver ability of the output stage
and notice the feedback path is negative.

 

[A.Anand Srinivasan]

from the pm you sent i feel that the cmfb which is dominated by the current is not enough as you are using very high resistors and the capacitance makes it all the more difficult...... so use lower value of resistors and if possible try reducing the capacitances involved....