Symbolic analysis of analog integrated circuits

In this paper we describe a new approach to simplification of symbolic expressions obtained using symbolic simulators. We use a combination of matrix-based and flow-graph based technique to generate signal flowgraphs that have frequency-dependent edge weights. The algorithm proceeds by first calculating the DC gain and then iteratively including frequency dependent terms that are significant in the frequency range of interest. This can be used to extract poles and zeroes together with a polynomial division procedure.