Time domain method for reduced order network synthesis of large RC circuits

In this paper we present a time domain method to approximate linear RC multiport networks, accurate up to user specified frequency. We use the Lanczos algorithm to compute eigenvalues, an electrical network based method to compute eigenvectors and use these to synthesize a reduced order RC network. A similar method for RC multiport approximation has been proposed by Yang and Kerns (1996), which works with admittance matrices (G and sC) of the multiport and also uses Lanczos algorithm to compute dominant eigenvalues and eigenvectors. However, their method forbids capacitor cutsets in the multiport, which is a common occurrence in multilayered interconnect modeling, signal integrity analyses etc. We propose an algorithm which works implicitly on the state matrix description of the network and allows capacitor cutsets in the graph of the network. We use an efficient DC analysis algorithm to make implicit computations of eigenvalues, eigenvectors and port admittance matrices