Characterization of Miniaturized Transformers at Varying Operating Power

The trend towards miniaturization and integration, observed in all the fields of electronics, also applies to systems requiring galvanic isolation. A key aspect is the development of miniaturized transformers, to be integrated at silicon level or package level in a SoC (System-on-Chip) or SiP (System-in-Package) approach. This paper proposes a methodology to characterize such micro-transformers through electromagnetic simulations, extracting a set of key performance parameters, the accuracy of which was experimentally verified. Results are valid under certain load conditions and rated power level but, in a real application, devices need the flexibility to work in a certain range of operating power with a negligible performance variation. Focus of the work is to evaluate the effect of this variable power. The transformers geometry was initially optimized for a rated power of 1W. Different transformer configurations have been tested with power ranging from 0.6 W to 1.4 W, and checking the variation in terms of voltage ratio and efficiency. Depending on the application, this variation can be impactful or negligible. Additionally, results have been compared with similar transformers optimized for each specific power level, to verify the improvement in case of a dedicated optimization.