BPFs with oct-resonance and -transmission-zero realized by coupling optimization on open-loop resonator

Abstract

This paper presents a series of novel designs for dual-band bandpass filters (BPFs) with excellent in-band and out-band filtering performances. By imbedding the spiral-line resonator into the coupling open-loop structures and adjusting the symmetrical structure, the second-order quad-mode BPFs are designed and then the fourth-order oct-mode dual-band BPFs. The final two designs possess eight resonant modes in the passband and also four/eight transmission zeros in the stopband, achieving a high transition-band selectivity with the roll-off rate over 1000 dB/GHz, broad out-band rejection from 1.5 GHz to 5.3 GHz (lower than 30 dB), and strong isolation between dual bands with the suppression level of 30 dB, operating at 3.2/3.4 GHz and 3.2/3.5 GHz respectively. Measured results agree well with simulations and prove the validity of the asymmetry feeders for multi-transmission-zero characteristics.

KEYWORDS:

• Dual-band bandpass filter
• open-loop resonator
• selectivity
• out-band rejection
• multimode resonator

Acknowledgements

This work was supported by the General Financial Grant from the China Postdoctoral Science Foundation (2020M671439, 2020T130283), National Natural Science Foundation of China (61903160), Natural Science Foundation of Jiangsu Province (BK20190581). This work was also partly supported by the 111 Project (B12018) and Fundamental Research Funds for the Central Universities (JUSRP51510).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by China Postdoctoral Science Foundation [grant number 2020M671439, 2020T130283]; Higher Education Discipline Innovation Project [grant number B12018]; National Natural Science Foundation of China [grant number 61903160]; Natural Science Foundation of Jiangsu Province [grant number BK20190581]. This work was also supported by the 111 Project (B12018) and Fundamental Research Funds for the Central Universities (JUSRP51510).

Notes on contributors

Xiao Wang

Xiao Wang was born in Baoding, Hebei Province, China in 1997. She received the B.Eng. degree in Computer and Communication Engineering from Northeastern University in 2019. She now studies for a master's degree in Electronics Science and Technology at Jiangnan University. Her current research interests are in design and development of radio frequency and microwave devices and humidity sensors.

Jun-Ge Liang

Jun-Ge Liang was born in Yantai, Shandong Province, China in 1991. He received the PhD degree in Electronic Engineering from Kwangwoon University (Korea) in 2018. He is currently working as associate professor at Jiangnan University, Wuxi, China. His research interests include the microwave devices. He received the Best Poster Award at ICAE 2017, the Silver Award at IFAAP 2018, and the Best Conference Paper Award at IEEE ICKII 2018.

He Jing

He Jing wan born in Beijing, China in 1983. He graduated from Beijing University of Posts and Telecommunications with a bachelor's degree and a master's degree. He currently works at the Academy of Broadcasting Science, National Radio and Television Administration. His current research interests include new media, network architecture and network security.

Jia-Kang Wu

Jia-Kang Wu was born in Huanggang, Hubei Province, China in 1995. He received the B.Eng. degree in Computer and Communication Engineering from Northeastern University in 2019. He now studies for a master's degree in Integrated Circuit Engineering at Jiangnan University. His current research interests are in design and development of radio frequency and microwave devices and humidity sensors.

Nam-Young Kim

Nam-Young Kim received the MS and PhD degrees in Electronic Engineering from the State University of New York (SUNY) at Buffalo, NY, USA, in 1991 and 1994, respectively, and the MS and PhD degree in Theology from Midwest University, St. Louis, MO, USA, in 2004 and 2006, respectively. He leads the RFIC and compound semiconductor-related research group at Kwangwoon University. He has authored or co-authored 175 refereed journal papers, 28 books, and 343 refereed conference papers. In addition, he holds over 116 patents, including semiconductor design patents.

Xiao-Feng Gu

Xiao-Feng Gu received the PhD degree in materials science and engineering from Johns Hopkins University, Baltimore, MD, USA, in 2003. He is currently a Professor of Microelectronics with Jiangnan University, Wuxi, China. His current research interests include reliability of semiconductor devices and circuits.