A Formal Approach to Verification of Linear Analog Circuits with Parameter Tolerances

a circuit with tolerance parameter fulfills a certain specification for all parameter combinations, because the tolerance parameters are modelled with a probabilistic density function, or the computed regions are non pessimistic approximations like convex polyhedrons. In contrast to the above, the proposed approach deals with intervals, enabling an exact proof of the correctness of the design. This contribution presents an approach to formal verification of linear analog circuits with parameter tolerances. The method proves that an actual circuit fulfills a specification in a given frequency interval for all parameter variations. It is based on a curvature driven bound computation for value sets using interval arithmetic. Some examples demonstrate the feasibility of our approach. The main idea of our procedure is to compare the value sets of the complex transfer functions Hspec and Hact. Related work in computing value sets can be found in [7, 8, 9,]. All these methods restrict the transfer functions to special classes, for example linear or multilinear dependent transfer functions [8], while our approach deals with a much larger class of transfer functions. Additionally, most of them deal only with outer bound computations of the value sets.