EMC filtering device comprising: - a printed circuit comprising at least two parallel layers (25, 26) of high permittivity material and at least three layers (20, 21, 22) of insulating material - the first layer of high permittivity material being positioned between a first layer of insulating material and a second layer of insulating material, the said first layer of high permittivity material comprising on one face in contact with the first layer of insulating material a negative plane and a positive plane, these two planes (80, 81) being connected on the side of a power supply and comprising on a face in contact with the second layer of insulating material an earthing plane, - the second layer of high permittivity material being positioned between the second layer of insulating material and the third layer of insulating material, the said second layer of high permittivity material comprising on a face in contact with the second layer of insulating material a positive plane and a negative plane, these two planes (82, 83) being connected to a line impedance stabilization network or to an electrical distribution network and comprising on a face in contact with the second layer of insulating material an earthing plane, the two layers (25, 26) of high permittivity material being parallel to one another and to the layers (20, 21, 22) of insulating material, - a magnetic core comprising three cylindrical arms (13, 14, 15) passing at right angles through the layers (20-22, 25, 26), the layers (20-22, 25, 26) each comprising three circular openings so that when the layers (20-22, 25, 26) are stacked, the circular openings form three cylindrical openings in which the three arms (13, 14, 15) of the core are positioned, - at least two windings (35, 36) wound around the first arm of the magnetic core, these windings (35, 36) and the first arm forming a first coil, - at least two windings (37, 38) wound around the second arm of the magnetic core, these windings (37, 38) and the second arm forming a second coil, the two coils (30, 31) being coupled coils, characterized in that the magnetic core comprises a gap dividing the arm that is positioned between the first and second arms into two arms (14.1, 14.2) and two plates parallel to the layers of the printed circuit (11, 12), each plate being positioned at one end of the three arms (13, 14, 15). - a printed circuit comprising at least two parallel layers (25, 26) of high permittivity material and at least three layers (20, 21, 22) of insulating material - the first layer of high permittivity material being positioned between a first layer of insulating material and a second layer of insulating material, the said first layer of high permittivity material comprising on one face in contact with the first layer of insulating material a negative plane and a positive plane, these two planes (80, 81) being connected on the side of a power supply and comprising on a face in contact with the second layer of insulating material an earthing plane, - the second layer of high permittivity material being positioned between the second layer of insulating material and the third layer of insulating material, the said second layer of high permittivity material comprising on a face in contact with the second layer of insulating material a positive plane and a negative plane, these two planes (82, 83) being connected to a line impedance stabilization network or to an electrical distribution network and comprising on a face in contact with the second layer of insulating material an earthing plane, the two layers (25, 26) of high permittivity material being parallel to one another and to the layers (20, 21, 22) of insulating material, - a magnetic core comprising three cylindrical arms (13, 14, 15) passing at right angles through the layers (20-22, 25, 26), the layers (20-22, 25, 26) each comprising three circular openings so that when the layers (20-22, 25, 26) are stacked, the circular openings form three cylindrical openings in which the three arms (13, 14, 15) of the core are positioned, - at least two windings (35, 36) wound around the first arm of the magnetic core, these windings (35, 36) and the first arm forming a first coil, - at least two windings (37, 38) wound around the second arm of the magnetic core, these windings (37, 38) and the second arm forming a second coil,