A Practical Design Consideration for Coupled-Resonator Laminated Band Elimination Filter Fabricated with LTCC of High Dielectric Constant

A practical design procedure of coupled-resonator band elimination filter (BEF) is studied. A small-sized BEF is fabricated with Low Temperature Co-fired Ceramics (LTCC) having high dielectric constant. Deterioration of band elimination characteristic due to approach of the constituent resonators is recovered with the proposed design procedure. But, in a practical fabrication process, additional physical restrictions are placed on this structure, e.g., the length and the impedance of inter-stage transmission line make another problem for its realization. They are overcome by adjustment based on computer simulation, and a fabricated LTCC BEF shows a good performance in an experiment carried out at the 2GHz-band.