Compact microstrip lowpass filter with wide stopband and sharp roll-off using tapered resonator

A Compact Lowpass Filter with Ultra Wide Stopband using Stepped Impedance Resonator

“…A higher suppression degree in the stopband leads to a greater SF. For instance, if the stopband bandwidth is calculated under -20 dB restriction, then the SF is considered as 2 [17]. Also, SBW is the stopband bandwidth with considering -20 dB rejection levels (SF = 2) for this work.…”

“…Also, SBW is the stopband bandwidth with considering -20 dB rejection levels (SF = 2) for this work. The relative stopband bandwidth (RSB) for -20 dB rejection level is given by [17]:…”

“…To increase the order of filter, more sections are needed, but increasing the sections will also raise the loss in the passband [2], [3]. With respect to these facts and to improve the performance of LPFs, various methods have been presented in [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. A wide stopband lowpass filter using U-shaped resonators has been fabricated in [3], which has a gradual transition band response.…”

“…However, with regarding to attenuation level of -20 dB, the stopband regions of these filters are not wide enough. A novel LPF with wide stopband and sharp roll-off using a tapered resonator has been fabricated in [17], which has a large circuit size.…”

Wide Band Stop Response Using Interdigital Capacitor/CSRR DGS in Elliptical Microstrip Low-Pass Filter

“…Most of these designs either suffer with low attenuation (<20 dB) range in the stop-band or have larger size. In addition, for better roll-off rate as well as compactness, an elliptical-function response is used in many LPFs which are based on several structures, such as stepped-impedance hairpin resonator [8], tapered resonator [12], slit-loaded tapered compact microstrip resonator cell [13], symmetrically loaded radial-shape patches and meandered transmission line [14], triangular patch resonators and radial patch resonators [15], symmetrically loaded triangular and high-low impedance resonators [16], P-shaped resonators [17], novel asymmetric structures for resonator and suppressor [18], wide stop-band using tri-section stepped impedance resonator [19] etc.…”