Case studies of mixed-signal DFT

Significant growth in demand for mixed signal parts, and an increased level of integration of such parts into SOCs have created or exacerbated several test related challenges. Techniques like design-for-testability (DFT) have been applied to overcome some of these challenges. In this paper, we present case studies of one of the most common DFT techniques for mixed-signal devices, namely, analog loopback testing of data converters. Theoretical analysis of loopback testing is presented, along with silicon test results for stand-alone, internal loopback and external loopback testing of data converter in an industrial chip. These results are used to evaluate the feasibility and effectiveness of these two variants of mixed-signal DFT, i.e., internal and external loopback testing of data converters.