An investigation of the electrical performance of an assembled SO8 package with a single-pole, double-throw (SPDT) switch is presented. Using an equivalent electric network for the whole assembly, the isolation and the insertion losses are computed for a signal frequency up to 5 GHz. From the modeling and simulation results, a significant effect of the path connection to ground is shown, and the required modifications of the connecting layout are discussed. The modeling concept is applicable to any single-chip package.<<ETX>>