Questions on Gain-boost telescopic cascode OTA

[jjboy]

I don't understand why should the BW of the gain-boost opamp be smaller than the second pole(p2) of the main opamp. In my opinion if the BW of the gain-boost opamp is much larger than p2 , the doublet will be out of the closed-loop BW of the main opamp and also the gain-boost loop can be stable.

 

[bbbb]

note that it is usually difficult to increase the BW of GB amp much higher than p2, it may require to bias the GB opamp at 1-2 order of magnitude higher current compared to the main opamp. And as you know no one likes to waste supply current!