Stable and efficient reduction of large, multiport RC networks by pole analysis via congruence transformations

A novel technique is presented which employs pole analysis via congruence transformations (PACT) to reduce RC networks in a well-conditioned manner. Pole analysis is shown to be more efficient than Pade approximations when the number of network ports is large, and congruence transformations preserve the passivity (and thus absolute stability) of the networks. The error incurred by reducing the networks is shown to be bounded by values which are fully selectable by the user. Networks are represented by admittance matrices throughout the analysis, and this representation both simplifies interfacing the reduced networks with circuit simulators and facilitates realization of the reduced networks using RC elements. A prototype SPICE-in, SPICE-out, network reduction CAD tool called RCFIT is detailed, and examples are presented which demonstrate the accuracy and efficiency of the PACT algorithm