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.