A Comparison of the S-parameter Extrapolation Methods

This article investigates five s-parameter extrapolation methods, i.e., Polynomial, Polynomial-Logarithmic, Linear, Static, and Zero-padding. The s-parameters extrapolated using these methods, along with the resulted impedance profiles and eye-diagrams are compared. The study reveals three key observations: First, in contrast to the conventional recommendation that s-parameter extrapolation should be avoided, extrapolation can be doable also useful provided the original s-parameter fulfilling certain conditions. Second, the widely adopted Static method and the Zero-padding method (when extrapolation is used) can exhibit less optimal performances in comparison to other extrapolation methods. Third, which extrapolation method to choose is a case by case decision to make. Practitioners need to carefully check the s-parameters before and after extrapolation in order to ensure the meaningful results can be obtained from the extrapolation.