Quasi-lumped bandpass filter with sharp transition edge and wide stopband rejection

• Published in: Electronics letters Vol. 49; no. 7; pp. 479 - 480
• Main Authors: Huang, H.-H, Chen, C.-H, Horng, T.-S
• Format: Journal Article
• Language: English
• Published: Stevenage The Institution of Engineering and Technology 28.03.2013; Institution of Engineering and Technology
• Subjects: Applied sciences; attenuation pole; band‐pass filters; band‐stop filters; BPF; Circuit properties; cross‐coupled path; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Exact sciences and technology; frequency 2.1 GHz; frequency 2.4 GHz; Frequency filters; highly miniaturised bandpass filter; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Microwave technology; multiple transmission zeros; passband selectivity; quasilumped bandpass filter; quasilumped LC resonators; resonator filters; resonator Q‐factor; sharp transition edge; third‐order coupled resonator design; UHF filters; WCDMA signal; wide stopband rejection; WLAN applications; attenuation pole; resonator filters; WCDMA signal; passband selectivity; UHF filters; third-order coupled resonator design; WLAN applications; frequency 2.4 GHz; band-pass filters; sharp transition edge; wide stopband rejection; highly miniaturised bandpass filter; cross-coupled path; quasilumped LC resonators; BPF; resonator Q-factor; multiple transmission zeros; band-stop filters; quasilumped bandpass filter; frequency 2.1 GHz; GHz range; Resonator; Q factor; LC circuit; Selectivity; Microwave filter; Energy gap; Wide band; Bandwidth; Transition; Band pass filter; Band stop filter; Passband
• ISSN: 0013-5194; 1350-911X; 1350-911X
• DOI: 10.1049/el.2012.4485

Presented is a highly miniaturised bandpass filter (BPF) with superior passband selectivity and high rejection over a wide stopband for 2.4 GHz WLAN applications. The proposed third-order coupled resonator design with a cross-coupled path provides an attenuation pole that is very close to the passband. Properly setting the fractional bandwidth and the resonator Q factor yields a sharp transition edge to suppress a 2.1 GHz WCDMA signal. Furthermore, the use of quasi-lumped LC resonators reduces the area of the BPF and generates multiple transmission zeros to enhance the desired stopband rejection.