US Patent 7312683 Symmetrical inductor

A symmetrical inductor. The inductor comprises first and second winding portions with a symmetrical arrangement and a coupling portion. Each winding portion comprises first, second, third and fourth semi-circular conductive lines arranged in concentricity and having first and second ends. The coupling portion comprises first and second pairs of connection layers, in which one pair are upper cross-connections and the other are lower cross-connections. The second ends of the first and fourth semi-circular conductive lines of the first winding portion are respectively connected to those of the second and third semi-circular conductive lines of the second winding portion by the first pair of connection layers. The second ends of the first and fourth semi-circular conductive lines of the second winding portion are respectively connected to those of the second and third semi-circular conductive lines of the first winding portion by the second pair of connection layers.