Using the technology of low temperature co-fired ceramic to design the dual-band bandpass filter

The novel dual-band bandpass filter is proposed in this letter. In order to miniaturize the size of the circuit and improve its performance, multilayered structure and the technology of low temperature co-fired ceramic (LTCC) are employed to design and fabricate the filter. Adopting the structure of a coupled line, two open-stub lines, and two capacitors, the transmission zeros can easily appear at the high side of two passband´s skirts. This result will increase the isolation between two passbands. The theorem of analysis is proposed in this letter. Finally, the measurements of the fabricated example are a good match with the simulation, which are evidence of the feasibility of filter configuration