volume | PIER Journals

Abstract

This paper introduces a balanced (differential) multiband reconfigurable (tunable) bandstop filter (BSF) using all lumped elements. The main features of the design include its ultra-compact size as well as flexibility to control any frequency band independently in terms of both center frequency and absolute bandwidth (ABW). In the proposed structure, the corresponding non-resonating nodes (NRN) of the symmetrical bisections are connected to N number of LC π-circuits (N-band cell) through capacitors. Again, in each symmetrical bisection, K number of NRNs are series cascaded through LC π-circuits. This results in a Kth order N-band stopband (notch) response in differential mode (DM) operation whereas provides a passband response when excited by a common mode (CM) signal. Reconfiguration of any DM stopband is obtained by using tunable capacitors for the corresponding LC π-circuit in each N-band cell and also, for its coupling capacitors to the NRNs. To validate the proposed topology, a dualband differential tunable BSF is designed and fabricated where both DM stopbands are controlled independently in the range of 1.16 GHz-1.32 GHz. Also, the bandwidth of each band is varied independently by 20-50 MHz without affecting the other band. At any tuning state, DM stopband rejection for each band is found to be ≥19 dB, resulting in a minimum CMRR value of 19 dB. The fabricated prototype occupies an area of 0.13λ_g×0.04λ_g (21 mm×7 mm) where λ_g is the guided wavelength at the center frequency of the entire spectral range, and the experimental results show a good agreement with the simulation results.

1. Khokle, R., R. Kumar, R. V. S. Ram Krishna, and N. Kushwaha, "Design and analysis of multi-band filters using slot loaded stepped impedance resonators," Progress In Electromagnetics Research B, Vol. 56, 137-160, 2013.
doi:10.2528/PIERB13091304 Google Scholar

2. Kamma, A., S. R. Gupta, G. S. Reddy, and J. Mukherjee, "Multi-band notch uwb band pass filter with novel contiguous split rings embedded in symmetrically tapered elliptic rings," Progress In Electromagnetics Research C, Vol. 39, 133-148, 2013.
doi:10.2528/PIERC13031202 Google Scholar

3. Chen, F., J. Qiu, and Q. Chu, "Dual-band bandstop filter using stub-loaded resonators with sharp rejection characteristic," Electronics Letters, Vol. 49, No. 5, 351-353, February 28, 2013.
doi:10.1049/el.2012.3752 Google Scholar

4. Wang, W., M. Liao, Y. Wu, and Y. Liu, "Small-size high-selectivity bandstop filter with coupled-line stubs for dual-band applications," Electronics Letters, Vol. 50, No. 4, 286-288, February 13, 2014.
doi:10.1049/el.2013.3704 Google Scholar

5. Shahrouzi, S. N., "Optimized embedded and reconfigurable hardware architectures and techniques for data mining applications on mobile devices,", Ph.D. Dissertation, University of Colorado Colorado Springs, December 2018. Google Scholar

6. Shahrouzi, S. N. and D. G. Perera, "Dynamic partial reconfigurable hardwarearchitecture for principal component analysis on mobile and embedded devices," EURASIP Journal on Embedded Systems, Vol. 2017, Article No. 25, Springer Open, February 2017. Google Scholar

7. Xie, J.-J. and Q. Song, "Wideband dual-polarized dipole antenna with differential feeds," Progress In Electromagnetics Research Letters, Vol. 59, 43-49, 2016.
doi:10.2528/PIERL16020101 Google Scholar

8. Yang, J.-R., H.-C. Son, and Y.-J. Park, "A class E power amplifier with coupling coils for a wireless power transfer system," Progress In Electromagnetics Research C, Vol. 35, 13-22, 2013.
doi:10.2528/PIERC12100914 Google Scholar

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

10. 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.
doi:10.1109/TCPMT.2018.2794993 Google Scholar

11. Borah, D. and T. S. Kalkur, "A planar multiband balanced bandstop filter," 2018 IEEE MTT-S Latin America Microwave Conference (LAMC 2018), 1-3, Arequipa, Peru, 2018. Google Scholar

12. Borah, D. and T. S. Kalkur, "Tunable multiband balanced bandstop filter with high CMRR," Progress In Electromagnetics Research C, Vol. 97, 1-13, 2019.
doi:10.2528/PIERC19041607 Google Scholar

13. Hunter, I. C., Theory and Design of Microwave Filters, IEE Press, London, U.K., 2001.
doi:10.1049/PBEW048E

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

15. Hong, J.-S., Microstrip Filters for RF/Microwave Applications, Wiley, Hoboken, NJ, 2011.
doi:10.1002/9780470937297

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, 2461-2468, October 2011.
doi:10.1109/TMTT.2011.2160965 Google Scholar

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

18. 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.
doi:10.1109/LMWC.2018.2805864 Google Scholar

19. Kong, M., Y. Wu, Z. Zhuang, and Y. Li, "Narrowband balanced absorptive bandstop filter integrated with wideband bandpass response," Electronics Letters, Vol. 54, No. 4, 225-227, February 27, 2018.
doi:10.1049/el.2017.4300 Google Scholar

Dr. Dubari Borah

Dr. Thottam S. Kalkur