A LTCC-based Ku-band 3D bandpass filter using stepped-impedance hairpin resonators

A new compact bandpass filter using stepped impedance (SI) hairpin resonators with multilayer configuration based on LTCC technology for Ku-band application is proposed. Two pairs of transmission zeros are achieved by introducing the cross coupling and asymmetric I/O structure, which can improve the rejection in the stop band. The compact filter is designed as a three-dimension structure which is embedded in the ceramic substrate based on the LTCC multilayer manufacturing technology. EM simulator HFSS is applied to design and optimize the proposed structure. The result shows a center frequency of 15.75 GHz with a bandwidth of 400 MHz. The insert loss is smaller than 2.1 dB, and the return loss is better than 18 dB within the passband. The overall dimension of the proposed filter is 4mm × 7.5mm × 1.056mm, about λ_g/2 × λ_g, which is suitable for the application in Ku-band integrated RF front end module.