Novel Miniaturized Dual-Band Bandpass Filter with High Suppression Using Low-Temperature Co-Fired Ceramic Technology

A novel low-temperature co-fired ceramic dual-band bandpass filter with a compact size and high selectivity is reported using vertically coupled lines and semi-lumped resonators. Due to the source-load coupling and the characteristics of the resonators, five transmission zeros are introduced to improve the selectivity of the filter. A dual-band filter located at 2.45 and 5.2 GHz has been designed and fabricated in a low-temperature co-fired ceramic substrate to verify the proposed design concept. With the assistance of the vertical coupling structure and low-temperature co-fired ceramic technology, the filter occupies an area of 7.3 × 6.2 mm 2 .