DDC112: DDC112

fA is probably very very hard if not impossible... And don't even know what kind of resolution you want to get. Haven't put a lot of thought but device noise is on fractions of fC, hence even with the longest integration times of 1s or so, you would just be barely above the noise. On top of that, you would have to compensate for the non-idealities at that level. For instance, leakage current is 0.1pA but even if you calibrate it out, you got to make sure temperature is stable as drift is 10fA/C. And so on... 

Don't know other devices that can do this unless you build it discretely...

Regards,

Edu