A Novel Balanced Bandpass Filter with Improved Stopband Characteristic using Low Temperature Co-fired Ceramic Technology

摘要

It is proposed a novel and simple second-order balanced bandpass filter using low temperature cofired ceramic (LTCC ) technology' in this paper . The proposed filter is mainly composed of two pairs of coupled-resonator and its performance includes a balun as well as a bandpass filter. In order to improve the selection around the passband , we add extra capacitors to the resonators and produce transmission zeros around passband by employing feedback capacitors between ports. The total size of proposed filter is 2.0mmXl.25mmX0.9mm , the center frequency is 2.45GHz. bandwidth is 100MHz, 51dB minimum at 88(M>60MHz. The simulation result showing promising application potentials in miniaturized mobile terminal, Bluetooth RF front-ends and wireless system.