Compact Combline Bandpass Filter Using LTCC Technology

A compact combline bandpass filter structure using low temperature co-fired ceramic (LTCC) technology is proposed. The lumped capacitance in traditional combline filter structure is changed to distributed capacitance realized by parallel coupled striplines in this structure. Combline filter with this structure can be constructed more easily and more compactly. A bandpass filter with this structure is designed in this paper. The simulation response exhibits an insertion loss of 1.9 dB,a return loss of 20 dB, and a relative band width of 8% with the center frequency at 9.6 GHz. The suppression at 8.4 GHz and 10.8 GHz is larger than 39 dB.