Compact balun

The present invention is directed to a compact balun device that includes an unbalanced port and a set of balanced differential ports. A first set of coupled transmission line structures is coupled to the unbalanced port and one port of the set of balanced differential ports. The first set of coupled transmission line structures is characterized by at least one device parameter and a first length that is substantially equal to a quarter of a wavelength (lambda). The wavelength (lambda) corresponds to a first frequency. A second set of coupled transmission line structures is coupled to another port of the set of balanced differential ports. The second set of coupled transmission line structures is characterized by the at least one device parameter and a second length that is substantially equal to the quarter of a wavelength (lambda). The wavelength (lambda) corresponds to the first frequency. A plurality of interconnections couples the first set of coupled transmission line structures and the second set of coupled transmission line structures. The plurality of interconnections are configured such that the compact balun operates at a reduced operating frequency, the reduced operating frequency being selected from a range of frequencies by varying at least one device parameter. The range of frequencies is approximately between one-sixth of the first frequency and one-half the first frequency.