High selectivity wideband bandpass filter based on stepped impedance open stubs loaded ring resonator

Dual-Band and Wideband Bandpass Filters Using Coupled Lines and Tri-Stepped Impedance Stubs

“…Bandpass filters are mainly transmission line-based passive devices that are used in many RF/microwave circuits and wireless communication and radar systems. They are essential front-end components that can pass signals within a certain frequency range and reject unwanted out-of-band signals [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. There are many parameters to be considered in the design and implementation of a bandpass filter, such as the design structure, size, passband frequency bandwidth, insertion loss, selectivity, roll-off rate, isolation, and stopband rejection.…”

“…This type of filter is excellent for multiple frequency systems such as carrier aggregation or wireless local area network (WLAN) bands. Another method for obtaining a wideband response is by modifying the filter structure or attaching other elements to increase the bandwidth—such a method works well for wideband applications [ 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ].…”

“…Single-band bandpass filters with a wideband response are another approach for increasing a filter’s bandwidth. Methods for obtaining a wideband response have been demonstrated in the literature and include the use of: folded multiple-mode resonators [ 19 ], dual-mode ring resonators [ 20 ], folded-arms square open-loop resonators [ 21 ], cross-shaped resonators [ 22 ], T-shaped resonators and L-shaped defected microstrip structures [ 23 ], and stepped impedance open stub-loaded ring resonators with a high selectivity response [ 24 ]. A bandpass filter with five poles in the passband and 58.3% 3 dB FBW was developed by employing a ring resonator loaded with stepped impedance open stubs [ 24 ].…”

“…Methods for obtaining a wideband response have been demonstrated in the literature and include the use of: folded multiple-mode resonators [ 19 ], dual-mode ring resonators [ 20 ], folded-arms square open-loop resonators [ 21 ], cross-shaped resonators [ 22 ], T-shaped resonators and L-shaped defected microstrip structures [ 23 ], and stepped impedance open stub-loaded ring resonators with a high selectivity response [ 24 ]. A bandpass filter with five poles in the passband and 58.3% 3 dB FBW was developed by employing a ring resonator loaded with stepped impedance open stubs [ 24 ]. A wideband bandpass topology consisting of shunt short-circuited stubs and half wavelength transmission lines was reported in [ 25 ]; the proposed filter configuration had a low selectivity factor of 0.62.…”

Staired-Slitted Flag Central Resonator Based Wide Band Bandpass Filter for Super Spurious Harmonic Suppressions

“…Techniques for improving the stopband suppression are analyzed in [26,27]. The fractional bandwidths of the filters in [28][29][30][31] are low. The outcome obtained from the aforementioned review is that there is still need for simple filter design methods that enable the easy realization of wideband filters with very low passband insertion loss, wide passband with very good selectivity, very good return loss in the passband, and spurious free stopbands.…”