Abstract:
A method of designing a BPF is proposed in this paper based on LTCC multilayer 3D technology,the centre frequence is at 880 MHz,the filter is realized by the structure of lump-parameter LC resonators and the distributed coupling to ensure the miniaturization and high performance.The filter concludes four LC parallel resonances and each two get the Electric coupling and magnetic coupling alternately to reach to a well stopband rejection character,then by bring the cross-couple between the number one and number four,we can get two transmission zeros to improve the stopband rejection character effectively.Using the circuit simulation and 3D Electromagnetic Fields simulation software,at last,the dimension of the filter is 4.5mm×4mm×1.5mm.The real result shows that the centre frequnece is 880 MHz,its bandpass is 160 MHz,insert loss is less than 2dB,VSWR is lower than 1.2,and the stopband rejection ismore than 25dB(0~700 MHz,1.1GHz~2GHz),the simulation and the measurement results have achieve a good agreement.