(12) United States Patent ao) Patent No.: Us 7,808,358 B2
Nakamura et al. (45) Date of Patent: Oct. 5,2010
An inductor includes a flat substrate and a conductor in a spiral shape having a plurality of turns. The plane on which the conductor is formed is substantially in parallel with a principal surface of the substrate. The turns of the conductor are equally spaced from each other in a direction parallel to the plane on which the conductor is formed. An outer one of the turns of the conductor is wider and thinner than an inner one of the turns of the conductor. A level of at least one of a top and a bottom of the conductor differs from one turn to another in a cross section vertical to the plane on which the conductor is formed.
12 Claims, 8 Drawing Sheets