Impact Rating of Layout Parasitics in Mixed-Signal Circuits: Finding a Needle in a Haystack

Parasitic couplings are the scourge of analoglmixed-signal (AMS) design sign-off. After the circuit has been verified, these layout-induced effects degrade the performance or even stability of the created system. In extreme cases, this may lead to malfunction under certain circumstances as for instance high-frequency electromagnetic interference (EMI). To verify the circuit by simulation, extraction is used to annotate the high number of parasitic elements to the circuit's netlist. Still, this tool does not point to a concrete coupling that causes the main impact on the performance. We propose an automated method to rate parasitic elements using a directed modification of the extracted post-layout netlist. By systematically removing parasitics and evaluating the performance, the designer is supplied with information about the main contributers to performance degradation. We demonstrate our approach by analysing and hardening an industrial voltage regulator layout with respect to EMI related influences.