Design based analog testing by characteristic observation inference

In this paper, a new approach to analog test design based on the circuit design process, called Characteristic Observation Inference (COI), is presented. In many situations, it is prohibitive to directly verify the circuit specifications due to the test equipment costs. Our approach considers a given universal set of reasonable input stimuli and measurements that can be performed with the given test equipment. From this universal set, a minimal number of measurements is automatically selected that represent a set of observations characterizing the state of the circuit under test with respect to parametric faults. A parametric fault model is introduced which is related to the individual circuit specifications. For each given circuit specification, a corresponding test inference criterion is computed, based on logistic discrimination analysis. By applying these criteria, the satisfaction or violation of the given circuit specifications can be inferred from the observations of the circuit under test. The COI method applied to a complex operational amplifier yields very encouraging simulated results with respect to parametric faults as well as to catastrophic faults.