volume | PIER Journals

Abstract

A simple balanced bandpass filter is presented. It is constructed mainly by a loop-type resonator with loaded shorted/opened stubs. The resonator is fed by the balanced coupled-line structure. In the loop-type resonator, three approaches can be simultaneously utilized to achieve high common-mode suppression. One is that the loop-type resonator has different differential/common-mode resonant frequencies, which results in a good in-band common-mode suppression. The second is that the loaded short stubs with different lengths will make the input/output port couplings to have different coupling strengths, which will deteriorate the common-mode bandpass response. The third is that loading the grounded resistors can effectively dissipate the common-mode signal. Meanwhile, loading the grounded resistors in the balanced coupled-line structure can effectively dissipate the reflective common-mode signal. A detailed description about its structure, operational mechanism and design method is given. For demonstration, a prototype balanced bandpass filter working at 2.4 GHz is designed, fabricated and measured. A high in-band common-mode suppression of 49 dB is achieved. The measured and simulated results can verify the effectiveness of the proposed balanced bandpass filter and the design method.

1. Ouyang, Z. A., L. Zhu, and L. L. Qiu, "Wideband balanced filters with intrinsic common-mode suppression using coplanar strip double-sided shunt-stub structures," IEEE Trans. Microw. Theory Techn., Vol. 69, No. 8, 3770-3782, 2021.
doi:10.1109/TMTT.2021.3077268

2. Zhang, S., L. Qiu, and Q. Chu, "Multiband balanced filters with controllable bandwidths based on slotline coupling feed," IEEE Microw. Wireless Compon. Lett., Vol. 27, No. 11, 974-976, 2017.
doi:10.1109/LMWC.2017.2750026

3. Wei, F., P. Y. Qin, Y. J. Guo, C. Ding, X. W. Shi, and , "Compact balanced dual- and tri-band BPFs based on coupled complementary split-ring resonators (C-CSRR)," IEEE Microw. Wireless Compon. Lett., Vol. 26, No. 2, 107-109, 2016.
doi:10.1109/LMWC.2016.2517125

4. Deng, H. W., L. Sun, Y. F. Xue, F. Liu, and T. Xu, "High selectivity and common-mode suppression balanced bandpass filter with TM dual-mode SIW cavity," IET Microwaves, Antennas & Propagation, Vol. 13, No. 12, 2129-2133, 2019.
doi:10.1049/iet-map.2018.6079

5. Zhu, J.-M., H.-W. Deng, Y.-K. Han, S.-B. Xing, and W. Han, "Compact triple-mode HMSIW balanced passband filter with intrinsic common-mode suppression," Microwave and Optical Technology Letters, Vol. 63, No. 7, 1803-1806, 2021.
doi:10.1002/mop.32827

6. Deng, H. W., Y. K. Han, L. Sun, J. M. Zhu, and S. B. Xing, "Multilayer dual-mode balanced SIW filter utilizing PECCPMC characteristic for common-mode suppression," IEEE Microw. Wireless Compon. Lett., Vol. 30, No. 9, 865-868, 2020.
doi:10.1109/LMWC.2020.3008933

7. Jin, C., J. X. Chen, H. Chu, Z. H. Bao, and , "X-band differential bandpass filter with high common- mode suppression using substrate integrated waveguide cavity," Electronics Letters, Vol. 50, No. 2, 88-89, 2014.
doi:10.1049/el.2013.2985

8. Li, P., H. Chu, D. Zhao, and R. S. Chen, "Compact dual-band balanced SIW bandpass filter with improved common-mode suppression," IEEE Microw. Wireless Compon. Lett., Vol. 27, No. 4, 347-349, 2017.
doi:10.1109/LMWC.2017.2678428

9. Fernandez-Prieto, A., A. Lujambio, J. Martel, F. Medina, F. Mesa, and R. R. Boix, "Simple and compact balanced bandpass filters based on magnetically coupled resonators," IEEE Trans. Microw. Theory Techn., Vol. 63, No. 6, 1843-1853, 2015.
doi:10.1109/TMTT.2015.2424229

10. Deng, H. W., T. Zhang, F. Liu, and T. Xu, "High selectivity and CM suppression frequency-dependent coupling balanced BPF," IEEE Microw. Wireless Compon. Lett., Vol. 28, No. 5, 413-415, 2018.
doi:10.1109/LMWC.2018.2811340

11. Chen, J., M. Du, Y. Li, Y. Yang, and J. Shi, "Independently tunable/controllable differential dual-band bandpass filters using element-loaded stepped-impedance resonators," IEEE Transactions on Components, Packaging and Manufacturing Technology, Vol. 8, No. 1, 113-120, 2018.
doi:10.1109/TCPMT.2017.2761789

12. Lee, C. H., C. I. Hsu, H. H. Chen, and Y.-S. Lin, "Balanced single- and dual-band BPFs using ring resonators," Progress In Electromagnetics Research, Vol. 116, 333-346, 2011.
doi:10.2528/PIER11033016

13. Liu, Q., J. Wang, G. Zhang, L. Zhu, and W. Wu, "A new design approach for balanced bandpass lters on right-angled isosceles triangular patch resonator," IEEE Microw. Wireless Compon. Lett., Vol. 29, No. 1, 5-7, 2019.
doi:10.1109/LMWC.2018.2884829

14. Yan, T., D. Lu, J. Wang, and X. Tang, "High-selectivity balanced bandpass filter with mixed electric and magnetic coupling," IEEE Microw. Wireless Compon. Lett., Vol. 26, No. 6, 398-400, 2016.
doi:10.1109/LMWC.2016.2562110

15. Yang, L., W. W. Choi, K. W. Tam, and L. Zhu, "Balanced dual-band bandpass filter with multiple transmission zeros using doubly short-ended resonator coupled line," IEEE Trans. Microw. Theory Techn., Vol. 63, No. 7, 2225-2232, 2015.
doi:10.1109/TMTT.2015.2431679

16. Hong, J. S. and M. J. Lancaster, Microstrip Filter for RF/Microwave Applications, John Wiley & Sons, 2001.
doi:10.1002/0471221619

17. Wang, H. and Q. X. Chu, "A narrow-band hairpin-comb two-pole filter with source-load coupling," IEEE Microw. Wireless Compon. Lett., Vol. 20, No. 7, 372-374, 2010.
doi:10.1109/LMWC.2010.2049426

18. Bockelman, D. E. and W. R. Eisenstadt, "Combined differential and common-mode scattering parameters: Theory and simulation," IEEE Trans. Microw. Theory Techn., Vol. 43, No. 7, 1530-1539, 1995.
doi:10.1109/22.392911

Dr. Jun-Mei Yan

Dr. Zhi-Peng Xiao

Professor Liangzu Cao