You are talking gain-bandwidth product of 20MHz. For a single stage amplifier, with a load of 12pF, this means a gm of 1.5mS (2.pi.fT=gm/CL). Assuming a gm/Id of at least 10, this gives us an Id of the input transistors of 150uA per transistor, which makes a total current of at least 300uA. So you need a class AB output stage to get and fT of 20MHz with that load and current consumption. Anyway, I guess it would be very difficult to reach such a goal.
Maybe with a gm/Id of 15 and a two- (or three-) stage configuration it can be possible. Is it on CMOS or bipolar?