Characteristics of a DC-DC Converter Using a Thin Film Microtransformer and a Microinductor

A thin-film microtransformer and a microinductor were fabricated, using photolithographic techniques for all processes. The microtransformer and microinductor are the same size, 3.5×3.9×0.06 mm
³
, and both have a layered structure with circular spiral windings between the upper and lower CoFeSiB films. The microtransformer and microinductor were mounted on a primary controlled forward converter, and the converter was operated at high frequencies between 6 and 10 MHz with a load resistance of 51 Ω; an output voltage of 1.9 V was obtained for an input voltage of 6 V. This result is important as a first step toward developing a microconverter in which transformers, inductors, capacitors, and rectifier diodes are integrated monolithically.