Patent ID: 8174336

Claim:
An ultra-wideband balun connected between an unbalanced line and a balanced line, comprising: a first transmission line formed on a first surface of a substrate, and configured such that a first end of the first transmission line is connected to a transmission line of the unbalanced line and a second end thereof is connected to a first one of transmission lines of the balanced line; a second transmission line formed on the first surface of the substrate, and configured such that the second transmission line extends from a first end of the unbalanced line, is arranged alongside of the first transmission line to be spaced apart therefrom by a certain distance, and is connected to a second one of the transmission lines of the balanced line; and a ground plane formed on a second surface of the substrate and configured such that the ground plane extends from a first end of the balanced line, is formed along the second transmission line, and is connected to a ground plane of the unbalanced line, wherein the second transmission line is connected to the ground plane of the balun through one or more vias that are perpendicular to the ground plane of the balun, and the ground plane of the balun is formed such that a width of a portion thereof adjacent to the unbalanced line is greater than that of a portion thereof adjacent to the balanced line.