Test generation for mixed-signal devices using signal flow graphs

We describe a new reverse simulation approach to analog and mixed-circuit test generation that parallels the digital test generation process. We invert the signal flow graph of the analog circuit, reverse simulate it with good and bad machine outputs, and obtain component tolerances, given circuit output tolerances. The inverted graph lets us backtrace from analog outputs to get analog input sinusoids that justify them. Mixed-signal circuits are easily tested using this approach, and we present test generation results for three analog circuits and two mixed-signal circuits. This analog backtrace method can generate tests for high-order analog circuits and non-linear circuits, which cannot be handled by existing methods because they lack a fault model and a backtrace method.