Rational function fitting of electromagnetic transfer functions of interconnect structures via extrapolation in time and interpolation in frequency

A new methodology is proposed for the rational function fitting of transfer functions of passive electromagnetic devices from numerically obtained and/or measured frequency-domain and time-domain response data. The proposed methodology combines the frequency-domain vector fitting process VECTFIT with its time-domain analog TDVF to yield a robust and versatile fitting algorithm for producing a rational function, broadband fit of the device response. The accuracy of the resulting algorithm is demonstrated through its application to the fitting of the admittance matrix of a lossy multi-conductor transmission line system.