When we teach about S-parameters and modeling, someone never fails to ask “What is causality?”  or “What happens if a model isn’t causal?”  Our go-to explanation is that it's a cause and effect thing: a system is causal if its output doesn’t respond before its input changes. In a causal universe, the light shouldn't turn on before you flip the switch. This seems straightforward. After all, if you're modeling or measuring a physical system — say, interconnects between a driver and receiver —...

Transient voltage responses of a PDN subjected to periodic step loads. Large signal measurements are essential to Power Distribution...