High Selectivity Cascaded Quadruplet Bandpass Filter with Three Pairs of Transmission Zeros

• Published in: Chinese Journal of Electronics Vol. 26; no. 5; pp. 1101 - 1104
• Main Authors: Chen, Jianfeng, Chen, Fuchang, Li, Runshuo, Xie, Zeming, Chu, Qingxin
• Format: Journal Article
• Language: English
• Published: Published by the IET on behalf of the CIE 01-09-2017
• Subjects: Bandpass filter; band‐pass filters; Cascaded quadruplet (CQ); Cross coupling; frequency 3.0 GHz; high selectivity cascaded quadruplet bandpass filter; Microstrip; microstrip Cascaded quadruplet bandpass filter; microstrip filters; microwave filters; poles and zeros; resonator filters; three‐quarter wavelength resonators; Transmission zeros
• ISSN: 1022-4653; 2075-5597
• DOI: 10.1049/cje.2017.07.017

A novel microstrip Cascaded quadruplet (CQ) bandpass filter using quarter wavelength resonators and three‐quarter wavelength resonators is proposed. Based on cross coupling and source‐load coupling, three pairs of finite transmission zeros are generated at the stopband. As a result, the out‐of‐band rejection can be enhanced and high selectivity is achieved. Based on the proposed structure, a cascaded quadruplet filter centering at 3.0GHz is designed and fabricated. Good agreement between the measured and simulated data is obtained.