Hi, i would suggest to study the book of mayer&gray (4th edt.; chapter 12 --> incl. a lot of design hints!) or even some papers.
In my opinion, take switched capacitor cmfb circuits since it is easier to design compared to the continous cmfb. For a simple estimation you can approximate your sc cmfb using an analog äquivalent (low pass filter).
Beside, don't make the same mistake as i! --> take into your design consideration of the ota the capacitive load of the cmfb!!!! more max. output current is required!
Generally, there are two types of CMFB circuit, SC or Continuoulsy one. Depending on your circuit, you can pick up one of them. SC type CMFB is easy to design and consume less power compared to Continuously one, but it require external CLOCK signal. You can refer to the book of "Analog Integrated Circuit Design" (I can not remeber exactly the auther's name, but I am sure they are from University of Toronto), there have clearly explanation.