EMI/RFI filter including a ferroelectric/ferromagnetic composite

An EMI filter (10) that makes use of a ferroelectric-ferromagnetic composite, member, or slab (12) in connection with capacitive and inductive elements. The geometrical structure of the filter (10) is such that the mutually orthogonal electric fields and magnetic fields generated by the capacitive and inductive elements penetrate the volume of the composite (12). In some designs, capacitive plates (14, 18, 32, 34) are split to avoid setting up eddy currents in the plates (14, 18, 32, 34) which oppose the penetration of magnetic flux through the composite (12). Various structural designs can be provided to define the capacitive elements and the inductive elements in different configurations relative to the composite to satisfy the desirable requirements. One particular low-pass design includes providing a slab (12) of the composite with plates (14, 18, 32, 34) on opposite sides of the slab (12) that define capacitors, and a conductive strip (20) wrapped around the slab (12) and electrically connected to the hot capacitive plates (14, 18) that define the inductor. This basic configuration can be extended to a cylinder (52) made of the composite, where a ground plane (56) is provided on one surface (54) of the cylinder (52), and the hot capacitor plates (60, 64) are provided on the other surface (62) of the cylinder (52), where a conductive strip (70) on the other surface (62) defines the coil. A multi-layer filter (76) can be provided that includes layered substrates (78) where metallized vias (80) extending through the substrates (78) define a coil, and ground planes (124) and capacitive plates (112, 114) on alternating substrates (78) define the capacitive elements.