DC tolerance analysis of electronic circuits by polyhedral circuits

Real equilibrium solutions of electronic circuits are affected by deviation of real characteristics of devices from their nominal values, producing the displacement of solution points from their nominal position. In this paper, a method to determine all the equilibrium regions in which real equilibrium points may fall is presented. The analysis is based on the introduction of the so-called strip characteristics that represent the characteristics of devices affected by tolerances. They are modeled by polyhedral characteristics. Different situations may occur as tolerances grow. A nominal solution point may disappear, or on the other end, some solution point not present with nominal characteristics may appear. These possible events call for a classification of the equilibrium regions in either certain or uncertain, depending on the existence or not of an equilibrium point for any choice of real characteristics. The algorithm adopts linear programming techniques and a clustering algorithm.