0.8 GHz to 2.4 GHz Tunable Ceramic Microwave Bandpass Filters

A 200% tuning range of advanced integrated piezoelectric LTCC bandpass filters is presented. The filter incorporates a novel parallel-plate capacitor that can be tuned by a piezoelectrically movable electrode. In this prototype, the fabrication process is modified for better controlling the air-gap inside the capacitor. To our knowledge, the potential recorded tuning range from 0.8 GHz to 2.4 GHz is the highest continuous range that ever reported in bandpass filters.