Common-Mode Choke Coil Using Mn-Zn-Ti Ferrite with Fe-Poor Composition

摘要

To enhance the electrical resistivity of a Mn-Zn ferrite markedly, Fe_2O_3 composition was reduced to less than 50 mol percent. Then to obtain good soft magnetic properties with this composition, TiO_2 was added to the component composition. We propose a Mn-Zn-Ti ferrite with Fe-poor composition, which has about 1,000 times higher resistivity and 100 times smaller Permittivity than conventional Mn-Zn ferrite with Fe-rich composition, athough it shows high initial permeability (4,500 at 100kHz). The common-mode impedance of the choke coil and the attenuation of the LC filter were investigated in order to compare this material with conventional Mn-Zn ferrite and Ni-Zn ferrite. I was found that this material was able to retain good magnetic properties in the high-frequency range the use of where Ni-Zn ferrite has been predominant. As a result, this material has potential for EMI applications over a wide frequency range which both conventional Mn-Zn ferrite and Ni-Zn ferrite have been used.