High-frequency power conversion is useful for miniaturization of power electronics, but requires low loss passive components to achieve high power densities without thermal issues.
At COMPEL 2017, we presented a paper (link for pdf) investigating the lowest achievable ESR and the highest achievable power capability of a resonant tank using an air-core inductor with a single-layer foil winding and commercially available capacitors. A loss model is presented and online catalogs of multilayer ceramic capacitors are searched for components that can provide a low ESR when combined with an optimally designed inductor for various resonance frequencies.
The resulting resonator has a measured sub-mΩ ESR and high efficiency with 250 V dc rating in a 1 cm3 volume. The resonant tank, when used in a resonant switched-capacitor converter, has kilowatt-range power capability. A power converter, using this resonant tank, will be limited by the power density of switches and interconnects rather than by passive components.