  DC microgrids are prone to small-signal instabilities due to the presence of
tightly regulated loads. This paper develops a decentralized stability
certificate which is capable of certifying the small-signal stability of an
islanded DC network containing such loads. Utilizing a novel homotopy approach,
the proposed standards ensure that no system eigenmodes are able to cross into
the unstable right half plane for a continuous range of controller gain levels.
The resulting "standards" can be applied to variety of grid components which
meet the specified, but non-unique, criteria. These standards thus take a step
towards offering plug-and-play operability of DC microgrids. The proposed
theorems are explicitly illustrated and numerically validated on multiple DC
microgrid test-cases containing both buck and boost converter dynamics.
