The emergence of mixed-signal (analog and digital) integrated circuits motivates the need for CAD tools supporting mixed-signal design and analysis. Furthermore, the presence of a large body of existing models in existing modeling language and the need for modeling mixed-signal (analog and digital) circuits motivates the need for a single unified simulation framework into which different parallel simulation subsystems can be easily connected. In this paper, we have review the design of a light-weight simulation backplane for integrating simulators from different domains. Of particular focus for this paper is the integration of a parallel SPICE (analog circuit) simulator called Xyce with a parallel VHDL (digital circuit) simulator called SAVANT.