Circuit diakoptic analysis based on order reduction of state equations

In this paper we present a new tearing technique to systematically formulate the state equations in symbolic normal-form for linear and/or nonlinear time-invariant large-scale analog circuits. The excess elements of the first and of the second kind are unitarily treated in order to allow a symbolic representation of the circuit with a minimum number of state variables. It is also presented a procedure to reduce the state equation number of each subcircuit The reduced-order is based on using an implicit integration algorithm and on successive elimination of the selected state variables. An example is given to illustrate the decomposition procedure, the assignment of the connection sources and the order reduction techniques.