Analysis of Fixture Design for Impedance Characterization ofMulti-Chip Power Modules

Advancements in wide bandgap semiconductor technology have accelerated the commercialization of high-performance multi-chip power modules. However, the fast edge rates of these devices are known to excite resonances within packaging parasitics, resulting in increased electromagnetic interference signatures and increased voltage stress. Accurate empirical characterization methods of these devices are necessary for device optimization and accurate system modeling. The complex and variable geometries of power modules make consistent characterization methods difficult and custom fixtures are often necessary to ensure measurement accuracy. This paper presents an example custom fixture design and confirms measurement accuracy with finite element analysis. The empirical measurements and simulation predictions demonstrate good agreement across frequency when module terminals are close together. However, several sources of error are identified and demonstrated when the module terminals are far apart.