Rethinking Basic Assumptions for Modeling Parasitic Capacitance in Inductors

This article rethinks the basic assumptions often used in analytically modeling parasitic capacitance in inductors. These assumptions are classified in two commonly-used physics-based analysis methods: the lumped capacitor network method and the energy conservation method. The lumped-capacitor network method is not the proper solution for calculating the equivalent parasitic capacitance in inductors at the first resonant frequency, but rather represents the equivalent parasitic capacitance above the last resonant frequency. The energy-conservation based method is shown to be more accurate and a reasonable solution to model the equivalent parasitic capacitance at the first resonant frequency. Multiple case studies of inductors are used for verifying the theory.