Measuring Dynamic Nonlinearity of Digitizers Affected by Time Base Distortion

Dynamic nonlinearity is a well-known major source of signal corruption in digital scopes and A/D conversion channels in general, particularly when dealing with fast signals and high sampling rates. This paper shows that the dynamic nonlinearity cannot be correctly measured without taking into account the systematic errors affecting the sampling instants (time base distortion) and presents two methods (nonparametric and parametric) to obtain accurate measurements in the presence of such errors. Both simulations and experimental results are provided to illustrate the problems arising with traditional methodologies and the accuracy of the proposed one.