Functional testing of circuits and SMD boards with limited nodal access

The author describes an approach to testing analog circuits which involves examining their transient response to step inputs in conjunction with multivariable discriminant analysis to determine individual component faults. Assuming the fault spectrum for an individual circuit can be obtained, appropriate pulse input stimuli can be chosen. On the basis of the device´s response to the pulse stimuli, relevant discriminants can be calculated. Together with the fault spectrum, the discriminants could characterize the various device faults, forming a database from which a discriminant analysis could classify such devices on the basis of these discriminants. This approach should yield a substantial savings in component testing time. The feasibility of this method has been examined for a simple circuit, while applications to more complex analog and digital circuit boards and VLSI circuits have been considered