I am doing my project about delta sigma modulation, it is needed a bandgap reference circuit for 2.5 voltage (because when changing VDD, my output is changed).
Is it possible for 2.5V bandgap circuit ? (my VDD is 3.3, using 0.13um tech).
I think in this case you would be better off with LDO-like structure. So make nice flat bgap and feed it as reference to ldo - this way you will have flat voltage over temp. You can generate 2.5V directly if you dump current reference to resistors - but I would think you will have a bit problem to compensate it over temp.
If the supply voltage is very stable, then using a resistor divider to get the reference voltage is feasible. Using Metal Film Resistors would alleviate much of the temperature drift.