Design of a miniaturized ultra wideband bandpass filter based on a hybrid lumped capacitors - distributed transmission lines topology

In this paper, a miniaturized UWB bandpass filter using a hybrid lumped capacitors-distributed transmission lines topology is designed. The filter design rules are carried out and a filter is optimized for a 3 dB fractional bandwidth of 127 % with criteria of compacity, matching and selectivity. A sensitivity study versus critical parameters is also given. The filter length is reduced to 0.18lambda @ 6.5 GHz in comparison with 0.54lambda for the distributed topology. The selectivity is improved with a shape factor equal to 1.28:1 instead of 1.46:1