Frequency-and Time-Domain-Based Methods to Estimate Parasitic Capacitances in Planar Magnetics using Terminal Measurements

Planar magnetic structures integrated into printed circuit boards are becoming preferred in various applications due to their high repeatability, good thermal performance, and efficient winding patterns. However, these structures are prone to high parasitic capacitances, especially at very high frequen-cies, due to the proximity of different PCB layers. Estimating the impact of parasitic capacitance on planar inductors and transformers is crucial as it defines their operational frequency range. Existing methods for estimating parasitic capacitance rely on physics-based and finite-element-based approaches, requiring specific computational software and detailed winding geometry. This paper introduces two new capacitance estimation methods based on terminal measurements of planar magnetic components. One method utilizes frequency-domain characteristics while the other leverages time-domain properties, both formulated with an approximate equivalent circuit model derived from fundamental network analysis principles. Both methods are validated through application to a planar magnetic prototype, demonstrating con-sistent and reliable results.