Thin film micro-transformers for future power conversion

This paper presents an investigation into the use of micro-fabricated transformers for future power conversion in the 5-10 MHz frequency range. The structure of the micro-transformers is described and an analytical model is used to optimize the transformer for maximum efficiency. The optimized devices are based on improved fabrication processes which give 80 /spl mu/m thick copper conductors and a two layer laminated magnetic core. The optimization suggests that an efficiency of 82% at an output power of 3.5 W can be achieved. Initial small signal results are presented for micro-transformers fabricated using the improved processes. The estimated efficiency of the fabricated microtransformer based on these results is 78%.