SIW Cavity Filters with Embedded Planar Resonators in LTCC Package for 5G Applications

Two three dimensional (3D) integrated System on Package (SoP) Low Temperature Co-fired Ceramic (LTCC) two-stage SIW single cavity filters with embedded planar resonators are designed, fabricated and tested. The embedded resonators create a two-stage effect in a single cavity filter. The design with a stripline ring around the center post of the cavity provides a 13% fractional bandwidth with a center frequency of 28.21 GHz, and with an insertion loss of −0.82 dB. The design that feeds at the middle of a stripline resonator provides a 15% fractional bandwidth at a center frequency of 28.12 GHz, and with an insertion loss of −0.53 dB.