The project was born with the idea of realize a current meter able to substitute the one already present in a test machine produced by the company "Crea Collaudi Elettronici Automatizzati Srl". This machine allows the user to make leakage current test on semiconductors. So my aim was realize a more precise and with more scale current meter to improve the machine behaviour. For do this was required a double project, one with a differential stage like a first stage and the other one with instead a trans-resistance stage, for admit a comparison. The first part of my project was create offset and noise models for all the part of my circuit to make possible the evaluation of compliance with specifications.