Patent ID: 8547186

Claim:
A compact balun device comprising: an unbalanced port and a set of balanced differential ports; a first set of coupled transmission line structures coupled to the unbalanced port and one port of the set of balanced differential ports, the first set of coupled transmission line structures being characterized by at least one device parameter and a first length that is substantially equal to a quarter of a wavelength (λ), the wavelength (λ) corresponding to a first frequency; a second set of coupled transmission line structures coupled to another port of the set of balanced differential ports, the second set of coupled transmission line structures being characterized by the at least one device parameter and a second length that is substantially equal to the quarter of a wavelength (λ), the wavelength (λ) corresponding to the first frequency; and a plurality of interconnections coupling the first set of coupled transmission line structures and the second set of coupled transmission line structures, the plurality of interconnections being configured such that the compact balun operates at a reduced operating frequency by selecting the at least one device parameter, the reduced operating frequency being within a balun operating bandwidth having a center frequency within a range of frequencies approximately between one-sixth of the first frequency and one-half the first frequency.