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Compact lowpass filter with high suppression level and wide stopband using stepped impedance m‐shape units
Author(s) -
Du Zebao,
Yang Hao,
Zhang Haiying,
Zhu Min
Publication year - 2014
Publication title -
microwave and optical technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 76
eISSN - 1098-2760
pISSN - 0895-2477
DOI - 10.1002/mop.28744
Subject(s) - stopband , cutoff frequency , low pass filter , electrical impedance , transition band , cutoff , materials science , acoustics , microwave , resonator , center frequency , filter (signal processing) , physics , optics , band pass filter , engineering , prototype filter , electrical engineering , optoelectronics , telecommunications , quantum mechanics
A lowpass filter (LPF) with high suppression level and wide stopband using novel stepped‐impedance m‐shape unit is presented. The low impedance section of center‐loaded stepped‐ impedance resonator is implemented using T‐shape open stub with three arms, which improve design freedom and reduce size simultaneously. The mechanism for rejection level and stopband width is analyzed based on one stepped‐impedance m‐shape unit. The implemented filter composed with three different unit exhibits 40‐dB rejection from 1.4 f c to 7.2 f c , where f c is 3‐dB cutoff frequency. The compact size of the cascaded LPF is as small as 0.25 λ g × 0.08 λ g , where λ g is guided wavelength at cutoff frequency. The measured results show good agreement according with simulated ones. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2947–2950, 2014