A Macromodeling Algorithm for Analog Circuits

The advantages of using macromodels of functional blocks in the simulation of large scale circuits have long been pointed out. However, all the methods for generating macrontodels that have so far appeared in the literature make very stringent assumptions about either the type of circuits to be modeled or the shape of the waveforms involved. The models generated in this way are, therefore, of limited use in general circuit simulation. In this paper we propose a general purpose macromodeling algorithm applicable to any type of circuit without any restrictions on the waveforms. Starting from a user-supplied template, the algorithm modifies the values and the branch characteristics of macromodel elements with the goal of optimizing the macromodel's time-domain accuracy. Experimental results obtained so far indicate that the algorithm requires reasonable amounts of CPU time and that the models are accurate enough to be used for standard circuit simulation.