Open AccessHigh‐selectivity tri‐band bandpass filter with ultra‐wide stopband
Author(s) -
Zhu Chuanming,
Xu Jin,
Kang Wei,
Wu Wen
Publication year - 2015
Publication title -
electronics letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.375
H-Index - 146
eISSN - 1350-911X
pISSN - 0013-5194
DOI - 10.1049/el.2015.2217
Subject(s) - stopband , passband , band pass filter , transition band , resonator , elliptic filter , coupling (piping) , physics , materials science , filter (signal processing) , prototype filter , optoelectronics , electronic engineering , acoustics , optics , low pass filter , engineering , electrical engineering , metallurgy
A tri‐band bandpass filter (BPF) with an ultra‐wide stopband is proposed. Based on tri‐mode unequal‐length shunted‐line stepped impedance resonators (SIRs), some extra resonator sections are added in unequal‐length shunted‐line SIRs to increase the degrees of freedom in extracting the coupling coefficients of the tri‐band BPF. Unequal‐length shunted‐line SIRs can provide an efficient way to obtain a tri‐band BPF with a small frequency ratio between the first two centre frequencies. Moreover, two transmission zeros can be achieved near every passband by employing cross‐coupling, resulting in high passband selectivity, excellent band‐to‐band isolation and an ultra‐wide stopband. As an example, a tri‐band BPF is demonstrated. Simulated results of the filter agree well with the measured ones.