Understanding S-Parameter vs Equivalent Circuit-Based Models for RLC Component Simulations in Keysight ADS and Genesys

For many years, S-parameter data files have been the default industry standard for representing passive surface mount devices in the microwave industry. In many cases, however, S-parameters fall short in terms of equipping designers with the simulation capability that is needed for circuit design success. In contrast, a properly extracted equivalent circuit model can avoid many inherent limitations of data file representations and provide for scaling, extrapolation, and statistical yield analyses not easily accomplished with S-parameters alone. This article discusses “best-practice” surface-mount component modeling from a number of points of view. Several examples are presented to illustrate common problems with S-parameter models and solutions that can be accomplished using a combination of modern tools. These tools include on-board RF probing, electromagnetic analysis and complex equivalent circuit modeling. The equivalent circuit models enable simulations that can very accurately represent microwave as well as mm-wave passive surface mount devices in ways that enable reliably successful circuit design flows from synthesis, through optimization and yield analysis to measured results that correlate well with simulation predictions.