Patent ID: 7567143

Claim:
A balanced-unbalanced transformation device comprising: a dielectric substrate having first and second opposing surfaces; first and second ¼ wavelength resonator transmission lines positioned on the first surface of the dielectric substrate, each having a first end short-circuited and a second end open-circuited; a ground electrode positioned on the second surface of the dielectric substrate; a ½ wavelength resonator transmission line positioned on the first surface of the dielectric substrate and having a first line portion disposed in a vicinity of the first ¼ wavelength resonator transmission line and a second line portion disposed in a vicinity of the second ¼ wavelength resonator transmission line, the ½ wavelength resonator transmission line having either end thereof open-circuited; a first balanced terminal connected to the first ¼ wavelength resonator transmission line; a second balanced terminal connected to the second ¼ wavelength resonator transmission line; an unbalanced terminal connected to the ½ wavelength resonator transmission line; and a balancing characteristic adjustment electrode having one end thereof connected to the ground electrode, the balancing characteristic adjustment electrode facing a side of a portion of the ½ wavelength resonator transmission line located between the first and second line portions.