Patent ID: 7209024

Claim:
A filter circuit comprising a first filter part and a second filter part which are connected in series each other, the first filter part including a first inductor and a first capacitor, the second filter part including a second inductor and a second capacitor, wherein the first inductor includes a center leg coil wound around a center leg of a magnetic core including the center leg and a plurality of outer legs, each of the outer legs configuring a loop magnetic path in common with the center leg while sharing the center leg, the second inductor includes an outer leg coil wound around the outer leg of the magnetic core, the outer leg coil includes a first outer leg coil part and a second outer leg coil part which are connected in series each other, the first outer leg coil part being wound around the outer leg configuring one of the loop magnetic paths, the second outer leg coil part being wound around the outer leg configuring the other loop magnetic path, the winding directions of the first and second outer leg coil parts are the same in polarity direction, the number of turns of the first outer leg coil part and that of the second outer leg coil part are equal to each other, and the outer leg coil is wound around the outer legs in a manner such that magnetic fluxes generated in the plurality of outer legs by current flowing in the outer leg coil cancel each other in the center leg part.