Passive Rational Fitting of a Passive Network Transfer Function From Its Real Part

127 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008.A methodology is presented to generate a rational function approximation of a passive network transfer function that makes use of sampled values of the transfer function's real part at a set of frequencies over the bandwidth of interest. For passive networks, real-part sufficiency describes the fact that the self and mutual impedance or admittance is uniquely defined in terms of the real part of the transfer function alone. Exploiting this property, we first demonstrate a methodology for the passive rational fitting of the self-impedance of a passive network. This is followed by the extension of the proposed methodology to the passive rational fitting of mutual impedances. Unlike other methodologies available, our methodology attempts to enforce passivity of the rational function by construction. Additionally, each of the elements of the matrix are fit independently in order to improve the numerical robustness and accuracy since the fitting is not restricted to a common set of stable poles. The accuracy and validity of the proposed methodology are demonstrated through their application to the fitting of several broadband, multiport transfer functions.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD