Effects of CMFB in FD amplifiers

[shuratox]

Hi,

I would like to know what is the main effects of CMFB on fully differential amplifiers besides the control of CM level. What is the specifications of the amplifier that the CMFB affects. Example: I know that to reach the maximum output swing, the CM level must be well defined. And the other specifications, how they change with the CMFB?
Thanks.

 

[kenambo]

If common mode levels are not well defined, It may appear as offset and makes unwanted signal variations at the output...

The high gain of the differential amplifier makes this offset into large change in the output...

it also affects the original replica of the input signal... and also causes the DC parameters of the differential amplifier to change...

In this case your result should be a non linear one...

Thanks,,..