This paper reports a test chip and an experimental method for characterizing the simultaneous switching noise (SSN) and the noise dependency on the ground pin assignment of a multilayer package. The SSN measurement was executed for various ground pin assignments. The measured results demonstrated that an extra electric current path of the displaced ground pin assignment enhanced the ground bounce due to increasing the effective inductance of package. A balanced pin assignment of the ground pins which suppressed the extra current path in the ground plane had a 20% reduction effect for SSN compared with conventional pin assignments. The extra current path of the ground plane was also verified by an electromagnetic field simulation. The modeling procedure was established for the noise estimation using the inductance value estimated by the field simulation. The circuit simulation resulted in a good agreement with the measured results, and the noise simulation method was applicable for the noise estimation at earlier stage of the package design.