SUMMARYThis paper illustrates a procedure for demonstrating and quantifying the importance of passivity in linear macromodels. This issue is critical whenever the macromodels are derived from tabulated port responses, either in time or frequency domain. We show an algorithmic procedure for the design of a passive termination network that will drive a given non-passive macromodel to instability. Several termination structures characterized by various port couplings are investigated. Relaxed passivity conditions are also given, which guarantee the stability of the macromodel under specific reduced-coupling loading conditions. Theoretical results are applied to a set of application test cases.