Frequency domain behavior of S <scp>‐parameters piecewise‐linear</scp> fitting in a <scp>digital‐wave</scp> framework

This paper describes PWLFIT+, an extension to the frequency domain of PWLFIT, a new paradigm in time-domain macromodeling for linear multiport systems, based on piecewise-linear (PWL) behavioral representation S-parameters step response. While impulse response each S-parameter is approximated as sum delayed rectangles (rect) functions, its spectrum interpolated corresponding cardinal sine (sinc) functions. Exploiting this correspondence, model building performed by iterative procedure where PWL macromodels can be determined order meet defined accuracy goals spectrum. At runtime, waves at ports are calculated using Segment Fast Convolution (SFC) algorithm within Digital Wave Simulator (DWS) framework. The proposed method characterized simplicity, stability, speed and scalability, all features that emphasized when it used DWS After analysis excellent numerical SFC Z-domain, clearly differentiated with respect conventional methods poles residues, two suitable application examples presented demonstrate unique PWLFIT+.