Multi-resonant microfabricated inductors and transformers

This paper introduces (1) a family of multi-resonant passive components with harmonically related impedance nulls and maxima, (2) board- and wafer-scale construction techniques for such structures, and (3) circuit topologies that exploit the harmonically related impedance extreme they provide. A three-dimensional copper electroforming process has been developed which offers an integrated-circuit designer larger-valued, higher-Q power inductors than are achievable with traditional thin-film processing. Such magnetic structures, whether fabricated in printed-circuit form or electroformed on a wafer, can be tapped to produce integrated multi-resonant L-C networks. These networks can develop much larger impedance than the corresponding untapped structure, provide self-shielding, eliminate switches from symmetric converter topologies, and otherwise reduce switch stresses. As part of the broader treatment, a new soft-switched radio-frequency power converter is introduced that demonstrates the reduction in peak device stress and passive-component size achievable with multi-resonant components. Taken together, the construction techniques, networks, and converter topologies presented here extend the power levels and applications for which passive components can be manufactured in an integrated fashion, alongside semiconductor switches and converter controls.