Abstract
A new structure of integrated low-pass LC filter of DC-DC power converter is proposed in this paper. This filter consists in a circular planar coil enclosed between two ferrites substrates. Mn-Zn ferrite has been chosen because of its high permeability and permittivity. In this filter Mn-Zn substrates act not only as a magnetic core but also as a capacitor. In order to reduce the conduction losses in the part of the ferrite used as a capacitor, a particular topology using a blocking layer is proposed. A modelling of the dielectric behaviour of the materials has been performed and injected in a simulation in order to find the resulting LC filter performances and its power range of use. In order to increase the filter efficiency, different solutions have been explored. In particular the inter-turn gap evolution has been optimized to reduce the inter-turn losses. Regarding the bulk losses, BaTiO3 blocking layers have been added, either upon the ground or the conductor. In this last case a co-firing ferrite tape has been inserted between turns to increase the LC product. Finally the use of low losses Mn-Zn and BaTiO3 has been proposed and the final characteristics (both electrical and dimensional) of our filter have been compared toconventional ones.
Highlights
Planar LC passive components, such as inductors and capacitors, have been implemented for many years using a variety of substrates, including standard PC boards, ceramics and silicon
A new structure of integrated low-pass LC filter of DC-DC power converter is proposed in this paper
Mn-Zn ceramic substrates have been used in this work for both their high permeability and permittivity
Summary
Planar LC passive components, such as inductors and capacitors, have been implemented for many years using a variety of substrates, including standard PC boards, ceramics and silicon This technology has been only used in low power devices (a few W) with working frequencies ranging up to a few GHz [1] [2] [3]. The Manganese-Zinc (Mn-Zn) ferrites exhibit a suitable high permeability (μr from 750 to 2 × 105) but above all a very high permittivity (εr about 104 at 1 MHz) compared with Nickel-Zinc ones (μr from 125 to 2 × 103 and εr about 25 at 1 MHz respectively) Despite this double property, they are exclusively used as core materials for inductors and transformers [4]-[8]. The LC filter plays an important role in the output voltage ripple value
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