LTCC BALUN FILTER USING TWO OUT-OF-PHASE FILTERING CIRCUITS

The invention presents a LTCC balun filter using two out-of-phase filtering circuits. The LTCC balun filter is comprised of three half-wavelength resonators and grounds which are located on fourteen metal layers. Vias are utilized to connect different metal parts. The first, fourth, seventh, eleventh and fourteenth metal layers are the ground. The three half-wavelength resonators are on the second, third, fifth, sixth, eighth, ninth, tenth, twelfth and thirteenth metal layers. By adjusting the coupling parts of the three half-wavelength resonators, namely the lengths of the seventh, eighth, ninth, tenth and eleventh layers, as well as the distances between them, the coupling strength between the half-wavelength resonators can be tuned. In addition, the quality factor of the circuit can be improved by tuning the port positions. By using the multi-layer LTCC technology, the present invention has the advantage of compact size, novelty, creativity and practicability.