BestFit: A SPICE-compatible model for efficient, passive, broadband transmission-line analysis of dispersive interconnects

BestFit refers to a mathematical methodology used for the direct passive synthesis of SPICE-compatible models of multi-conductor interconnect structures. Given the bandwidth of simulation, the length of the interconnect system, and its per-unit-length, frequency-dependent resistance, inductance, capacitance and conductance matrices, the proposed algorithm synthesizes a compact, multi-port, dispersive, SPICE-compatible model for the interconnect. The resulting model is in terms of a concatenation of a number of non-uniform segments of lumped passive circuit representations of the per-unit-length series impedance and shunt admittance matrices, the lengths of which are obtained as a result of a Pade-Chebyshev approximation of the frequency-dependent input impedance matrix of the multiconductor transmission line system. The synthesized circuit is "optimal" in the sense that highly-accurate responses can be obtained with A number of segments per minimum wavelength barely exceeding the Nyquist limit of 2.