SYMBOLIC ANALYSIS OF LARGE ANALOG CIRCUITS USING A SENSITIVITY-DRIVENENUMERATION OF COMMON SPANNING-TREES

A new approach for the generation of approximate symbolic network func tions is presented. This approach is used to analyze large analog inte grated circuits. It is based on a matroid intersection algorithm that directly enumerates common spanning trees of a two-graph representatio n of a given circuit. The approximation algorithm is based on an inspe ction of the sensitivity of the magnitude of a network function with r espect to the different coefficients of a network function. These sens itivities as a function of frequency control the enumeration process. In this way, the algorithm enumerates a minimum number of the dominant terms for each coefficient of the network function. The complete algo rithm runs in O(k mn(3)) time, in which K is the average number of mat roid intersections that must be generated for the approximation of eac h coefficient of the network function, n is the number of nodes in the linearized network and m the number of circuit elements, At the end o f the paper experimental results are presented. These results indicate that this new approach is superior to other approaches to generate an approximate symbolic network function from a given two-graph.