buffer spec for sigma-delta modulator or sc filter

[mists]

in general, we use op buffers to give vref+ and vref- for sigma-delta modulator feedback input or sc filter input. but how to define the op buffer's spec if we know sc intergrator's accuracy and operation frequency, such as buffer's Gain, bandwidth etc. thanks!

 

[haoshs]

I want to know the question also.
Especially the driver spec of buffer.
THX ad.