Novel design of a compact band-pass filter with two finite transmission zeros using LTCC technology

A novel method to design a compact low-temperature co-fired ceramics (LTCC) lumped-element second-order band-pass filter with two finite transmission zeros is proposed in this paper. The filter model is established according to the capacitor coupling resonance band-pass filter´s circuit structure and the connect type of embedded coupling capacitor was neatly designed to make it be linked between input port and output port. The simulation results show that two transmission zeros are produced by the common grounded inductor between two resonators. This band-pass filter has a compact structure and occupies an area of only 2mm × 1.2mm × 0.95mm according to the package size of 0805. After the physical model and inner structure of the BPF are established, the samples are fabricated by LTCC technology. The measurement results show that the insertion loss is less than 2.5dB and return loss is less than -20dB at the center frequency of 2.45GHz, which agree basically with the simulation results.