Implementation of different layouts of a coreless planar transformer for a flyback converter

In this paper is shown the implementation of different layouts of a coreless planar transformer for a flyback converter. In addition, a 0.5W DC/DC converter was developed. The converter is based on a flyback converter for simple applications. The transformer is designed in a form as a spiral coil on a PCB. The special feature of the converter is that the flyback converter is laid out without a core. The area (diameter) of a spiral coil should be bigger as a coil with a core because the air is not a good energy store. The advantage of a coreless transformer is the PCB-Design. An analysis shows some results by different geometry and frequency of the planar transformer.