The spectral technique in controllability/observability measures of digital circuits

With the rapid increase of IC size, the testability of ICs must be taken into account in their design phase, so that the testability measure of the circuit under design can be kept as low as possible before test generation. The problem of how to determine the testability measure of a circuit is discussed. Circuits are analyzed on a module level rather than a gate level. A technique is then given by which the controllability/observability spectra and therefore the testability measure of a circuit can be derived from the given spectra of the modules in the circuit. This technique alleviates the testability design problem for large-scale integration