it is not difficult to integrate femtoamp current to a measurable voltage by using a small capacitor integrator, however, when it comes to differentiate charge to current, problems appear since the differentiation can significantly magnify noise. here is my question: is the capacitor integrator the only way to measure femtoamp current, if yes, is there any good ways to differentiate the numerical data? if no, could you please give me some hints on how to measuring fA current without using capacitor integrator?
Thanks