Design of 40GHz multilayer end coupled band pass filter using LTCC technology

Multilayer end coupled band-pass filters (BPFs) using Low Temperature co-fired Ceramic (LTCC) technology have been presented as a parts of 40 GHz Remote Antenna Unit Downlink for Radio over fiber (RoF) system applications. In order to control the precise distance between two adjacent resonators, the resonators was vertically located on different layers. The BPFs were designed and fabricated by using Ferro A6S tape. Its dielectric constant and loss tangent are 5.8 and 0.002, respectively, at 40GHz. The overall size of the fabricated filter was 10.5 × 2.5 × 0.77 mm3. The measured insertion and return loss were 3.17dB and 18.53dB at 42GHz, respectively.