Compact dual-mode dual-band bandpass filter with wide stopband for WLAN applications

• Published in: Electronics letters Vol. 51; no. 17; pp. 1372 - 1374
• Main Authors: Xu, Li-Jie, Zhang, Gang, Tang, Yi-Ming, Bo, Ya-Ming
• Format: Journal Article
• Language: English
• Published: The Institution of Engineering and Technology 20.08.2015
• Subjects: Bandpass filters; band‐pass filters; band‐stop filters; circuit size; Circuits; compact dual‐mode dual‐band bandpass filter; coupled circuits; coupled input structure; coupled output structure; dual mode dual band BPF; dual‐band performance; dual‐mode excitation; frequency 2.4 GHz; frequency 5.2 GHz; Joining; Local area networks; microwave filters; microwave resonators; primary passband; resonator filters; Resonators; ring resonator; second passband; shorting via; Simulation; Skirts; spurline; transmission zero; UHF filters; vias; wide stopband; Wireless communications; wireless LAN; wireless local area network; Wireless networks; WLAN application; coupled input structure; resonator filters; coupled output structure; dual-mode excitation; dual mode dual band BPF; ring resonator; vias; frequency 2.4 GHz; band-pass filters; primary passband; band-stop filters; compact dual-mode dual-band bandpass filter; transmission zero; microwave resonators; dual-band performance; UHF filters; spurline; wireless local area network; second passband; circuit size; WLAN application; microwave filters; wide stopband; shorting via; frequency 5.2 GHz; wireless LAN; coupled circuits
• ISSN: 0013-5194; 1350-911X; 1350-911X
• DOI: 10.1049/el.2015.1913

A compact dual-mode dual-band bandpass filter (BPF) for WLAN applications is presented. On the basis of a primary passband formed by a ring resonator, a second passband is introduced by taking advantage of its tightly coupled input and output structures. Therefore, a dual-band performance is achieved without increasing the overall circuit size. Shorting vias and spurlines are adopted separately to realise the dual-mode excitation of each passband. Finally, a compact dual-mode BPF centred at 2.4 and 5.2 GHz is designed and fabricated, along with four transmission zeros, leading to sharp skirts and a wide stopband. Experimental results reveal good agreement with simulation results.