Design method for dual-band filters with completely independent passbands

ABSTRACT

A design method for transmission-line-based dual-band filters with completely independent passbands is demonstrated. The proposed method completely ignores the conventional restrictions imposed on the electrical lengths of the transmission lines. Consequently, each resonator is designed separately by the predetermined parameters. Unlike conventional dual-band filters, the susceptance slope parameters at two center frequencies do not need to be maintained in all sections. As a result, the proposed filter can be designed to not only have different bandwidths, but also different responses. In addition, tuning the J-inverter values increases the design’s flexibility and compensate the theoretical limitation. The experimental results for various filters verify the proposed method, including the outstanding passband insertion loss. For the first time, a filter with a Chebyshev response in one passband and a maximally flat time-delay response in the other is demonstrated in this work.

Keywords:

• Bandpass filter
• dual-band filter
• independent passband
• maximally flat time-delay filter
• multi-band filter

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Jungje Ha  http://orcid.org/0000-0001-8831-0633

Additional information

Funding

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2011-0016802).

Notes on contributors

Taejun Lim

Taejun Lim obtained his BS degree in electrical and electronic engineering from Yonsei University, Seoul, Korea, in 2013, and is currently working toward his PhD degree in electrical and electronic engineering at Yonsei University. His current research interests include high-performance microwave circuits and non-radiative wireless power transfer techniques.

Jungje Ha

Jungje Ha was born in Jinju, Gyeongnam, Korea in 1985. He received the BS, MS and PhD degrees from Yonsei University, Seoul, Korea, in 2009, 2011 and 2017, respectively. He is currently a Senior Researcher with the Agency for Defense Development, Daejeon, Korea. He received Gold Award in 2012 Qualcomm-Yonsei Innovation Award and Grand Prize in 2015 Creative Design Competition For Future Radio Wave. His current research interests include multi-band planar circuits for microwave applications and electromagnetic scattering analysis of electrically very large structures.

Seungku Lee

Seungku Lee received the BS and MS degrees in electrical and electronic engineering from Yonsei University, Seoul, South Korea, respectively, and the PhD degree in electrical engineering from the University of Michigan, Ann Arbor, MI in 2016. He is currently working for Broadcom, CA as an acoustic filter design engineer.

Yongshik Lee

Yongshik Lee was born in Seoul, South Korea. He obtained his BS degree from Yonsei University, Seoul, in 1998, and MS and PhD degrees in electrical engineering from the University of Michigan, Ann Arbor, MI, USA, in 2001 and 2004, respectively. In 2004, he was a Post-Doctoral Research Associate with Purdue University, West Lafayette, IN, USA. From 2004 to 2005, he worked at EMAG Technologies, Inc., Ann Arbor, as a Research Engineer. In 2005, he joined Yonsei University, where he is currently a Professor. His current research interests include passive and active circuitry for microwave and millimeter-wave applications, electromagnetic metamaterials, and non-radiative wireless power transfer techniques. He was a visiting scholar at the University of California, Davis, in 2013–2014.