Modeling and Dimensioning of a Planar Inductor for a Monolithic Integration

This article presents a new approach which enables us to deal with the problem of dimensioning of a square spiral planar inductor with a ferromagnetic core and a silicon substrate; for its monolithic integration in a micro converter DC-DC step-down of Buck type. By drawing on the model of Yue and Yong, we designed a new electric model of a planar spiral inductor with a core and substrate, that we will name inductor "MOFS" (metal - oxide - ferrite - semi-conductor). This model enables us to present the different parasitic effects generated by the core and the substrate. We present also various technics to reduce the losses in the substrate. As well as the design of a new approach "approach of doping". This approach allows us to play on the doping of silicon to reduce or increase as we need the resistive and capacitive effects in the substrate, which are due to the semi conductivity of silicon. This technic is based on the doping of silicon either in donor atoms or acceptor atoms.