A study on stray capacitance modeling of inductors by using the finite element method

Stray capacitance modeling of an inductor is essential for its RF equivalent circuit modeling and inductor design. Stray capacitance determines an inductor's performance and upper frequency limit. A method has been proposed for modeling the distributed stray capacitance of inductors by the finite element method and a node-to-node lumped capacitance network. The effects of wire insulation layer, ferrite core, number of segments used to model the circumference of a wire cross section, pitch and coil-to-core distances, and the capacitance between nonadjacent turns, etc., an an inductors' self-capacitance and calculation accuracy, have all been considered. The calculated equivalent lumped stray capacitance for a rod inductor with a ferrite core is compared to that estimated from measurement. Good agreement between them has been observed.