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.