Patent ID: 7116185
Filing Date: 2006-10-03
Classification: H03H

Abstract:
1. A balun comprising: an unbalanced terminal for receiving and outputting unbalanced signals; a first balanced terminal and a second balanced terminal for receiving and outputting balanced signals; a low-pass filter provided between the unbalanced terminal and the first balanced terminal; a high-pass filter provided between the unbalanced terminal and the second balanced terminal; and a layered structure including dielectric layers and conductor layers alternately stacked, wherein: the low-pass filter and the high-pass filter include a total of at least three coils and a total of at least three capacitors; the at least three coils are disposed opposite to the at least three capacitors, with one of the dielectric layers in the layered structure disposed between the coils and the capacitors; the at least three coils are disposed in locations that do not overlap one another when seen in a direction orthogonal to the layers of the layered structure; each of the at least three coils includes a plurality of coil-forming conductor layers that are disposed on different ones of the dielectric layers of the layered structure and connected via at least one through hole; and the at least three capacitors are formed using a plurality of capacitor-forming conductor layers disposed on at least three of the dielectric layers of the layered structure, and at least one of the plurality of capacitor-forming conductor layers is disposed in a location sandwiched by other two of the plurality of capacitor-forming conductor layers located above and below, and is shared among a plurality of capacitors.