Patent ID: 8598964

Claim:
A balun comprising: a planar first transmission line including a planar first conductor having opposite first and second major faces and a second conductor, the first conductor having a first end for conducting a signal relative to a circuit ground and a second end for conducting a balanced signal, the second conductor having first and second ends, the first end of the second conductor being open-circuited and disposed proximate to the first end of the first conductor, the second end of the second conductor being open-circuited and proximate to the second end of the first conductor; a planar second transmission line including the second conductor and a planar third conductor extending in a plane parallel to a plane of the first conductor and having opposite first and second major faces, the third conductor being spaced from the first conductor, and having a first end proximate to the first end of the second conductor and connected to the circuit ground and a second end for conducting the balanced signal; a planar first ferrite layer spaced from the first and third conductors and extending continuously from opposite to the first major face of the first conductor to opposite to the first major face of the third conductor in a first plane parallel to the planes of the first and third conductors; and a planar second ferrite layer spaced from the first and third conductors and extending continuously from opposite to the second major face of the first conductor to opposite to the second major face of the third conductor in a second plane parallel to the planes of the first and third conductors, the first and third conductors being disposed between the first and second ferrite layers; the second conductor being spaced from the first and third conductors and spaced from the first and second ferrite layers, the second conductor including planar first and second conductor layers, the first conductor layer extending opposite and along the first major faces of the first and third conductors in a third plane parallel to the planes of the first and third conductors and disposed between the first ferrite layer and the first and third conductors, and the second conductor layer extending opposite and along the second major faces of the first and third conductors in a fourth plane parallel to the planes of the first and third conductors and disposed between the second ferrite layer and the first and third conductors, the second conductor also including portions extending between the first and second conductor layers spaced from the first and third conductors.