Compact Ultra-Wideband Low-Temperature Co-Fired Ceramic Bandstop Filter Using Semi-Lumped Resonators

Abstract

A novel ultra-wideband bandstop filter with three semi-lumped resonators based on low-temperature co-fired ceramic technology is presented. Stopband rejection depth and bandwidth are controlled by the elements of each resonator. The filter not only has controllable transmission zeros, but it also features compact size due to the low-temperature co-fired ceramic 3-D structure and meandered topology. In addition, multi-layer capacitors are employed to enlarge the capacitance without size increments. A lossless transmission line model analysis is used to derive design equations. To validate the proposed structure, a multi-layer bandstop filter centered at 3.2 GHz with bandwidth of over 85% is designed and built. Good agreement between measured and simulated results is obtained.