Abstract
The recent voltage regulators in mobile apparatus have been required to be small size, thin thickness and low power dissipation. We have developed new DC-DC convertors which includes a micro inductor using CoFeSiB/SiO2 multi-layer film. This paper describes the electronic characteristics of the magnetic thin film core with magneto wire and evaluates the operating characteristics of a DC-DC convertor using micro inductors. High inductances and down sizing of the inductors are compatible when the three dimensional winding helical coil and the multi-layer film are used. The micro inductors show high inductances of 14〜15 μH and high quality factors of 10〜20 at a frequency of 1 MHz. The DC-DC convertor modules which have some components such as an inductor, capacitors and a power IC of a switching frequency of 1 MHz have achieved a high efficiency of about 90% at an input and an output voltage of 4V and 1.5V, respectively.
