Patent ID: 8283991

Claim:
A broadband balun, comprising: an unbalanced transmission line portion, including a first in-phase trace extending along a longitudinal axis, a first anti-phase trace extending parallel to the first trace, and at least one ground plane parallel to, electromagnetically coupled with, and physically isolated from each of the first in-phase and anti-phase traces; a balanced transmission line portion, the balanced transmission line portion including a second in-phase trace in electrical communication with the first in-phase trace, and a second anti-phase trace in electrical communication with first anti-phase trace, each of the second in-phase and anti-phase traces vertical parallel plates (or co-planar) with its respective first in-phase and anti-phase traces and substantially uncoupled to the at least one ground plane; and a transition region disposed between the unbalanced transmission line portion and the balanced transmission line portion, the transition region comprising a respective terminal edge defining a boundary of each of the at least one ground planes between the unbalanced and balanced transmission line portions and a ground plane edge variation extending along the longitudinal axis for a predetermined length measured from the respective terminal edge, wherein respective cross sections of each of the unbalanced, balanced and transition regions are substantially symmetric with respect to the longitudinal axis.