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Tunable Multiband Balanced Bandstop Filter with High CMRR

By Dubari Borah and Thottam S. Kalkur
Progress In Electromagnetics Research C, Vol. 97, 1-13, 2019


A novel and effective architecture of tunable multiband balanced bandstop filter (MBBSF) is introduced for the first time in this paper. Each symmetrical bisection of the proposed branch line structure consists of K series cascaded tunable N-band sections to realize a reconfigurable K-th order N-band response in differential mode (DM) operation. The main advantage lies on the fact that all these N bands can be tuned simultaneously or each band independently. Moreover, it maintains a high common mode rejection ratio (CMRR) for all the tuning states by incorporating open stubs in the symmetrical plane of the balanced structure. To validate the proposed topology, a balanced dualband tunable BSF is designed where the two DM stopbands tune in the range of 1.16 GHz-1.29 GHz and 1.6 GHz-1.76 GHz, respectively. The lower and the upper bands maintain a constant absolute bandwidth (ABW) of 115 MHz and 135 MHz, respectively, and stopband rejection is better than 20 dB for each band. The fabricated prototype occupies an area of 0.31λg2, and the experimental results show a good agreement with the simulation results.


Dubari Borah and Thottam S. Kalkur, "Tunable Multiband Balanced Bandstop Filter with High CMRR," Progress In Electromagnetics Research C, Vol. 97, 1-13, 2019.


    1. Hagag, M. F., M. Abdelfattah, and D. Peroulis, "Balanced octave-tunable absorptive bandstop filter," 2018 IEEE 19th Wireless and Microwave Technology Conference (WAMICON), 1-4, Sand Key, FL, 2018.

    2. Chen, P., P., L. Li, K. Yang, K. Hua, and X. Luo, "A microstrip dualband bandstop filter with dualband bandstop resonators," 2017 IEEE 17th International Conference on Communication Technology (ICCT), 1685-1688, Chengdu, 2017.

    3. Aldeeb, H. and T. S. Kalkur, "A novel tunable dual-band bandstop filter (DBBSF) using BST capacitors and tuning diode," Progress In Electromagnetics Research C, Vol. 67, 59-69, 2016.

    4. Subramanyam, G., M. Cole, N. Sun, N. Sbrockey, G. S. Tompa, and T. S. Kalkur, "Complex oxide based electronics," Journal of Applied Physics, Vol. 114, 191301-1 to 35, 2013.

    5. Muhhamad, A., T. S. Kalkur, and N. Cramer, "1 GHz active phase shifter based on tunable high-dielectric constant BST thin films," IEEE Microwave and Guided Letters, Vol. 16, 261-263, 2006.

    6. Cai, J., Y. J. Yang, W. Qin, and J. X. Chen, "Wideband tunable differential bandstop filter based on double-sided parallel-strip line," IEEE Transactions on Components, Packaging and Manufacturing Technology, Vol. 8, No. 10, 1815-1822, 2018.

    7. Sorocki, J., I. Piekarz, S. Gruszczynski, and K. Wincza, "Low-loss directional filters based on differential band-reject filters with improved isolation using phase inverter," IEEE Microwave and Wireless Components Letters, Vol. 28, No. 4, 314-316, April 2018.

    8. Kong, M., Y. Wu, Z. Zhuang, Y. Liu, and , "Narrowband balanced absorptive bandstop filter integrated with wideband bandpass response," Electronics Letters, Vol. 54, No. 4, 225-227, February 22, 2018.

    9. Psychogiou, D., R. Gómez-García, and D. Peroulis, "Fully adaptive multiband bandstop filtering sections and their application to multifunctional components," IEEE Transactions on Microwave Theory and Techniques, Vol. 64, No. 12, 4405-4418, December 2016.

    10. Gómez-García, R. and A. C. Guyette, "Reconfigurable multi-band microwave filters," IEEE Transactions on Microwave Theory and Techniques, Vol. 63, No. 4, 1294-1307, April 2015.

    11. Hong, J.-S., Microstrip Filters for RF/Microwave Applications, Wiley, Hoboken, NJ, 2011.

    12. Sagawa, M., M. Makimoto, and S. Yamashita, "Geometrical structures and fundamental characteristics of microwave stepped-impedance resonators," IEEE Transactions on Microwave Theory and Techniques, Vol. 45, No. 7, 1078-1085, July 1997.

    13. Chen, F., R. Li, J. Qiu, and Q. Chu, "Sharp-rejection wideband bandstop filter using stepped impedance resonators," IEEE Transactions on Components, Packaging and Manufacturing Technology, Vol. 7, No. 3, 444-449, March 2017.

    14. Hunter, I. C., Theory and Design of Microwave Filters, IEE Press, London, U.K., 2001.

    15. Pozar, D. M., Microwave Engineering, Wiley, Hoboken, NJ, 2012.

    16. Ou, Y. and G. M. Rebeiz, "Lumped-element fully tunable bandstop filters for cognitive radio applications," IEEE Transactions on Microwave Theory and Techniques, Vol. 59, No. 10, 246-2468, Oct. 2011.

    17. Boutejdar, A., S. Elhani, and S. D. Bennani, "Design of a novel slotted bandpass-bandstop filters using U-resonator and suspended multilayer-technique for L/X-band and WLAN/WiMAX applications," 2017 International Conference on Electrical and Information Technologies (ICEIT), 1-7, Rabat, 2017.

    18. Elsbury, M. M., P. D. Dresselhaus, S. P. Benz, and Z. Popovic, "Integrated broadband lumped-element symmetrical-hybrid N-way power dividers," 2009 IEEE MTT-S International Microwave Symposium Digest, 997-1000, Boston, MA, 2009.

    19. Boutejdar, A. and A. Omar, "A miniature 5.2-GHz bandstop microstrip filter using multilayer-technique and coupled octagonal defected ground structure," Microwave Opt. Technol. Lett., Vol. 51, 2810-2813, 2009.

    20. Boutejdar, A. and S. Bennani, "Design and fabrication of tri-stopband bandstop filters using cascaded and multi-armed methods," Advanced Electromagnetics, Vol. 6, No. 3, 18-24, 2017.

    21. Boutejdar, A. and A. Omar, "Miniaturized lowpass and bandstop filters using controlled coupling of open-loop-ring defected ground structure ," Microw. Opt. Technol. Lett., Vol. 52, No. 11, 2575-2578, 2010.