A compact quasi-lumped LTCC band pass filter for C-band wireless application

A integrated quasi-lumped band pass filter (BPF) for C-band wireless application was designed and fabricated using low temperature co-fired ceramic(LTCC) technology. The circuit is based on the quasi-lumped filter topology, and made of two inductive-coupled resonator filter circuit´s with a feedback capacitor while all of the elements is placed in the three dimension form.In BPF´s design, a wideband circuit design method has been adopted. The BPF´s performance has been simulated and optimized by finite element method(FEM). A experimental LTCC BPF has been made and measured. The measured results of the tested BPF agreed very well with the simulation frequency responses, and the measurement results show the BPF´s insertion loss is less than l.ldB, the return loss is less than -12 dB, the ldB bandwidth is larger than 1 GHz bandwidth at the center frequency of 5.5 GHz. Its good performance, small size and relatively simple structure make it a good candidate as an integrated filter for various LTCC system.