Improving coverage of simulation-based verification by dedicated stimuli generation

Simulation-based verification is still the most frequently used technique when complex designs are to be verified. Stimuli are thereby generated and applied in order to sufficiently trigger and, by this, verify a set of considered scenarios. In general, a scenario can be triggered in various fashions. To ensure a high verification quality, each of these fashions should adequately be covered. However, to the best of our knowledge, this has not appropriately been addressed thus far, i.e. existing stimuli generation is mainly performed without an explicit consideration of the possible fashions in which a scenario might be triggered. To improve this, three approaches are proposed in this work. While examples illustrate their advantages, a case study confirms that, using the proposed approaches, very compact sets of stimuli satisfying this coverage requirement can efficiently be generated.