Commonmode feedback circuit poles compensation in differential Active RC Filter

[sudeep_]

Hi,

Can any one suggest me to remove the poles in CMFB circuit loop in differential opamp. This poles are appeared due to the filter feedback network. The CMFB circuit has shown below, and Loop gain and phse shift.

I noticed that SR did not change in the Filter due to instability of CMFB.

 

[D.A.(Tony)Stewart]

1st pole is 1/(RssCss)
2nd pole is 2gm/Css

RdsOn*Css is a figure of merit , almost constant , lower is better.


here is another approach, more analytical
**broken link removed**