  We introduce a robust numerical technique to verify the causality of sampled
scattering parameters given on a finite bandwidth. The method is based on a
filtered Fourier transform and includes a rigorous estimation of the errors
caused by missing out-of-band samples. Compared to existing techniques, the
method is simpler to implement and provides a useful insight on the time-domain
characteristics of the detected violation. Through an applicative example, we
shows its usefulness to improve the accuracy and reliability of macromodeling
techniques used to convert sampled scattering parameters into models for
transient analysis.
