Miniaturized LTCC bandpass filter using transmission line dual-mode resonator

For the first time, a 3-dimentional (3-D) transmission line dual-mode resonator is proposed by using the low temperature co-fired ceramic (LTCC) technology. The proposed dual-mode resonator is reasonably folded in both vertical and horizontal directions for constructing a miniaturized bandpass filter (BPF), which overcomes the vital shortcoming of large circuit size of the LTCC distributed-element circuits. The size of the designed BPF centered at 2.45GHz is only 2.7×2.6×1.6mm³. Two transmission zeros are realized in both sides of the passband. The simulated and measured results with good agreement are presented to verify the proposed idea.