Ultra-Wideband Differential Bandpass Filter With Narrow Notched Band and Improved Common-Mode Suppression by DGS

A novel microstrip ultra-wideband (UWB) differential filter with narrow notched band based on the transversal signal- interference concept is presented. In order to enhance the interference immunity from undesired signals efficiently, the notched band is implemented by coupling with quarter wavelength shorted-line at input and output ports. By taking advantage of the bandgap characteristic of defected ground structure (DGS), a slot-line DGS is used for improving the common-mode rejection. In this work, at the center frequency of the notched band which is 2.45 GHz, about 7.3% bandwidth (2.35-2.53 GHz) is realized by full-wave simulator. Agreement between experiment and simulation is observed.