Design of Low‐Temperature Co‐Fired Ceramic‐Based Miniaturized Filter With High Rejection for Super High‐Frequency Band Applications

ABSTRACT A super high‐frequency (SHF) bandpass filter was designed and fabricated using low‐temperature co‐fired ceramic (LTCC) technology. To achieve miniaturization while suppressing undesired coupling effects that can generate spurious resonances and parasitic responses, a multilayer configuration was implemented, in which capacitive and inductive elements were allocated to specific layers and regions. Through utilizing the parasitic interactions between components, the number of discrete elements was reduced. Transmission zeros were introduced to enhance out‐of‐band (OoB) suppression through tailored routing of interconnecting lines, and mutual inductive coupling between inductors. The design was optimized using full‐wave three‐dimensional electromagnetic simulations. The fabricated LTCC filter exhibits a passband of 3.0–3.4 GHz with an OoB rejection exceeding 50 dB. Measured results are in good agreement with simulations, confirming the suitability of the proposed approach for SHF‐band applications.