This study focuses on the design and the realization of an integrated EMI filter embedded in an aircraft power supply. The first part of the study is dedicated to the modeling of the dc-dc power, based on a "black box" representation: the converter is represented by an association of sources and impedances that reflect its external EMI behavior. This initial step enables us to define the electrical structure of the filter and the component values; a hybrid solution (active plus passive) can be effective for optimal filtering while minimizing the size and mass. The second part of the study is devoted to its realization, based on the integration of capacitive and inductive components inside a printed circuit board structure. This technology is named hybrid integration. Some technological difficulties are highlighted regarding the geometry of the components and their manufacture using this technology. Finally, filter architecture is proposed and a functional prototype is realized. Experiments show that significant gains in volume are achieved while compliance with the DO 160 standard (aeronautics) is obtained.