The use of linear models in A/D converter testing

This paper demonstrates how a linear modeling technique can be applied to three common methods for testing analog-to-digital converters (ADC's)-the servo-loop method, the tally-and-weight method, and the code density method-to improve their efficiency and accuracy. In order to compare the accuracy of the test procedures that incorporate the linear modeling technique with the corresponding procedures that do not, confidence intervals are derived for the integral and differential nonlinearity (INL and DNL) estimates obtained in both cases. Since the linear model may itself introduce some error in the estimates, the accuracy of the model must be determined in order to make the comparisons meaningful. This is accomplished by using a nested experimental design to determine how much of the variance in the transition levels is accounted for by the model.