This paper presents a Design-for-Test (DfT) approach for folded ADCs. A sensor DfT circuit is designed to sample several internal ADC test points at the same time, so that, by computing the relative deviation among them the presence of defects can be detected. A fault evaluation is done considering a behavioral model to compare the coverage of the proposed test approach with a functional test. Afterwards, a fault simulation is used on a transistor level implementation of the ADC to establish the optimum threshold limits for the DfT circuit that maximize the fault coverage figure.