The use of passive components has experienced significant growth in recent decades, particularly in the field of mobile telephony and embedded electronics. The work presented in this Thesis is part of a project between the LT2C laboratories of UJM and Ampère of INSA LYON. The objective of this thesis is the modeling of signal micro-transformers used to isolate the power (Driver IC) and control (JFET or MOSFET) parts. The points addressed in this thesis are the choice of transformer structures which meet the project requirements, the development of a transformer model which takes into account in particular the losses and the evolution of the permeability of the Magnetic Material and the different capacitive couplings. . Simulations using HFSS were carried out in order to design the selected structures and validate the developed model. Manufacturing steps compatible with those of microelectronics were used to fabricate one-layer and two-layer prototypes of magnetic material with different configurations. A high frequency characterization (2MHz-200MHz) using the vector network analyzer was carried out and finally a comparative study between the simulation results and the measurement results is the subject of a presentation.