Compact Ultra-wideband Bandpass Filter with Wide Fractional Bandwidth and High Skirt Selectivity

Abstract

A compact ultra-wideband bandpass filter having highly selectivity and wide bandwidth simultaneously is proposed, which adopts a modified multiple-mode resonator (MMR) and annular structures. The modified MMR is constructed by multiple uniform-impedance stubs and a dumbbell-based stepped-impedance stub. Two transmission zeros are created by the dumbbell-based stepped-impedance stub at the lower and upper cutoff frequencies to improve the selectivity. Additionally, two annular defected ground structures in the aperture ground are adopted to enhance the coupling factor and reduce the etching size. This bandpass filter has a fractional bandwidth of 127% with selectivity of up to 0.939. The measured results are in good agreement with the simulation results. 39Zhibin Zeng, Ph. D., Associate Professor and Master's Tutor, School of Microelectronics, Xidian University. As a technical leader, he has completed the design of wireless Bluetooth system, wireless WIFI system and signal integrity circuit. He has published more than 10 articles on EI and SCI, and applied for more than 10 patents. At present, research has been carried out in the fields of high-speed circuit design, embedded systems and high-speed integrated circuits.How to cite this paper: Lei Bai, Yi-qi Zhuang, Zhi-bin Zeng, " Compact Ultra-wideband Bandpass Filter with Wide