Comparison of fields emitted from high frequency silicon-integrated, microfabricated inductors

Technological progress and development is bringing commercially available power supplies integrated in a single chip closer and closer to reality. One of crucial milestones in this process is integration of inductors with magnetic core onto a silicon substrate. Such inductors enable full integration of a switch mode voltage converter in a single chip, provided that the switching frequency is high enough. This significant increase of switching frequency creates new problems for IC designers and engineers, especially related to electromagnetic interferences and compatibility. This paper presents simulated electromagnetic fields emitted by two commonly used designs of magnetic core inductors and an air core coil of corresponding inductance. Comparison of emitted fields is based on simulation results obtained with Ansoft Maxwell 3D. The aim of the work is to determine levels of radiation in silicon die and above it in order to identify problems that may rise in IC design, as well as exploring the feasible advantages and drawbacks of possible shielding.