Understanding S-Parameter Vs Equivalent Circuit-Based Models For RLC Component Simulations With NI/AWR Microwave Office

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 onboard 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 using National Instruments (formerly AWR) Microwave Office.