volume | PIER Journals

2017-08-08

A Simple Bandpass Filter with Independently Tunable Center Frequency and Bandwidth

Bo Zhou,

Dr. Bo Zhou

Xidian University

China

Homepage

Jing-Pan Song,

Dr. Jing-Pan Song

Collaborative Innovation Center of Information Sensing and Understanding at Xidian University, and Science and Technology on Ant

Xidian University

China

Homepage

Feng Wei,

Prof. Feng Wei

Xidian University

China

Homepage

Xiao-Wei Shi

Professor Xiao-Wei Shi

School of Electronics Engineering

Xidian University

China

Homepage

Progress In Electromagnetics Research Letters, Vol. 69, 113-118, 2017

doi:10.2528/PIERL17061502 | Google Scholar

Abstract

A varactor-tuned microstrip bandpass filter (BPF) with independently tunable center frequency and bandwidth is proposed in this paper. The proposed BPF with a simple configuration is composed of a half-wavelength transmission line with both ends short-ended and a T-shaped transmission line. Meanwhile, two varactors are inserted symmetrically in the middle section of the half-wavelength transmission line to adjust the resonant frequency. The T-shaped transmission line is connected to the half-wavelength transmission line by a lumped capacitor. In addition, two inductors loaded symmetrically in the feed line are employed to control the coupling coefficient. It is convenient to adjust the frequency and bandwidth of the filter independently by using only three varactors, which simplifies the circuit structure greatly. The predicted results on S parameters are compared with the measured ones, and a reasonable agreement is achieved.

Download Full Article (669) View Full Article volume

Citation

Copy Export

Bo Zhou, Jing-Pan Song, Feng Wei, and Xiao-Wei Shi, "A Simple Bandpass Filter with Independently Tunable Center Frequency and Bandwidth," Progress In Electromagnetics Research Letters, Vol. 69, 113-118, 2017.
doi:10.2528/PIERL17061502

References

1. Wang, X.-G., Y.-H. Choand, and S.-W. Yun, "A tunable combline bandpass filter loaded with series resonator," IEEE Trans. on Microw. Theory and Tech., Vol. 60, No. 6, 1569-1576, 2012.
doi:10.1109/TMTT.2012.2189123 Google Scholar

2. Cheng, C.-C. and G. M. Rebeiz, "A three-pole 1.2-2.6-GHz RF MEMS tunable notch filter with 40-dB rejection and bandwidth control," IEEE Trans. on Microw. Theory and Tech., Vol. 60, No. 8, 2431-2438, 2012.
doi:10.1109/TMTT.2012.2198231 Google Scholar

3. Yang, T. and G. M. Rebeiz, "Tunable 1.25-2.1-GHz 4-pole bandpass filter with intrinsic transmission zero tuning," IEEE Trans. on Microw. Theory and Tech., Vol. 63, No. 5, 1569-1578, 2015.
doi:10.1109/TMTT.2015.2409061 Google Scholar

4. Chiou, Y.-C. and G. M. Rebeiz, "A tunable three-pole 1.5-2.2GHz bandpass filter with bandwidth and transmission zero control," IEEE Trans. on Microw. Theory and Tech., Vol. 59, No. 11, 2872-2878, 2011.
doi:10.1109/TMTT.2011.2164619 Google Scholar

5. Renedo, M. S. and R. G. Garcia, "A tunable combline filter with continuous control of center frequency and bandwidth," IEEE Trans. on Microw. Theory and Tech., Vol. 53, No. 1, 191-199, 2005.
doi:10.1109/TMTT.2004.839309 Google Scholar

6. Wang, Y., F. Wei, H. Xu, and X.-W. Sh, "A tunable 1.4-2.5GHz bandpass filter based on single mode," Progress In Electromagnetics Research, Vol. 135, 261-269, 2013.
doi:10.2528/PIER12111704 Google Scholar

7. Chiou, Y.-C. and G. M. Rebeiz, "Tunable 1.55-2.1GHz 4-pole elliptic bandpass filter with bandwidth control and > 50 dB rejection for wireless systems," IEEE Trans. on Microw. Theory and Tech., Vol. 61, No. 1, 117124, 2013.
doi:10.1109/TMTT.2012.2227789 Google Scholar

8. Huang, X.-G., J.-Q. Zhang, Y.-Q. Lin, and Q.-Y. Xiang, "Design of a six-pole tunable band-pass filter with constant absolute bandwidth," 2016 Progress in Electromagnetic Research Symposium (PIERS), 3507-3510, Shanghai, China, August 8-11, 2016. Google Scholar

9. Zhang, X., C. Chen, M. Li, W. Chen, and J. Cai, "Tunable tri-band bandpass filter using varactor-tuned stub-loaded resonators," 2016 Progress in Electromagnetic Research Symposium (PIERS), 4228-4232, Shanghai, China, August 8-11, 2016. Google Scholar