Design of Six-Order Bandpass Filter Realized by LTCC

Using the simulation software Ansoft HFSS, a LTCC bandpass filter design with a steep side band was constructed with three-dimensional model.Based on the design of the t sixth-order filter,multi-transmission zeros at low frequency and high frequency were introduced by adding cross-coupling between non-adjacent resonators level,it can greatly improving the stopband rejection.Combined with circuit simulation and three-dimensional electromagnetic simulation,a sixth-order bandpass filter with size of 4.5mm * 3.4mm * 1.5mm was designed and produced,it’s center frequency is 3.325 GHz and the bandwidth is 170 MHZ,the measured results and simulation results are in good consistency.The filter size is very small as a result of LTCC multilayer structure,and it is a standard SMD components encapsulation,so it can be widely used in the mobile communications system.