In this paper, an integrated switchable and tunable bandpass filter is designed, simulated, and fabricated. This integrated bandpass filter is able to switch as well as tune in the ultra-wideband (UWB) as well as 2.4 GHz band. At first, a UWB bandpass filter is developed which consists of two bent shorted quarter-wavelength stubs and a connecting half-wavelength stub. Subsequently, a 2.4 GHz bandpass filter is realized by connecting another half-wavelength stub on top of the UWB filter. RF pin-diodes are used for switching the bands between UWB and 2.4 GHz bandpass filter. The switchable bandpass filter converts into a tunable filter by changing the inductance or the length of shorted stubs through the pin diodes. A detailed parametric analysis is done for calculating different stubs lengths of the UWB as well 2.4 GHz bandpass filter. The simulation results show a high rejection level of >40 dB at the lower frequency and a low insertion loss of 0.8 dB in the passband for UWB filter. For 2.4 GHz bandpass filter, the simulation results show an insertion loss of 0.42 dB and a 3 dB bandwidth of 796 MHz. The filter is fabricated on a Rogers 4003 substrate, and the measurement results of the switchable filter in the UWB band show an insertion loss of 2.1 dB and a 3 dB bandwidth of 7 GHz. In the case of 2.4 GHz bandpass filter, the insertion loss is 0.78 dB.
1. Tamjani, A. A., L. Dussopt, and G. M. Rebeiz, "Miniature and tunable filter using MEMS," IEEE Trans. Microwave Theory Tech., Vol. 51, 1878-1885, 2003. doi:10.1109/TMTT.2003.814317
2. Karim, M. F., A. Q. Liu, A. Arokiaswami, and A. B. Yu, "A tunable bandstop filter via the capacitance change of micromachined switches," Journal of Micromechanics & Microengineering, Vol. 16, 851-861, 2006. doi:10.1088/0960-1317/16/4/023
3. Karim, M. F., Y.-X. Guo, Z. N. Chen, and L. C. Ong, "Miniaturized reconfigurable and switchable filter from UWB to 2.4 GHz WLAN using PIN diodes," International Microwave Symposium, IEEE Microwave Theory and Techniques Society (MTT-S), 509-512, Boston, USA, 2009.
4. Brown, A. R. and G. M. Rebeiz, "A varactor tuned RF filter," IEEE Trans. Microwave Theory Tech., Vol. 48, 1157-1160, 2000. doi:10.1109/22.848501
5. Pal, B. and S. Dwari, "Microstrip dual-band bandpass filter with independently tunable passbands using varactor-tuned stub loaded resonators," AEU - International Journal of Electronics and Communications, Vol. 73, 105-109, March 2017. doi:10.1016/j.aeue.2017.01.004
6. Supavarasuwat, P., M. Kumngern, S. Sangyaem, W. Jaikla, and F. Khateb, "Cascadable independently and electronically tunable voltage-mode universal filter with grounded passive components," AEU - International Journal of Electronics and Communications, Vol. 84, 290-299, February 2018. doi:10.1016/j.aeue.2017.12.002
7. Fourn, E., et al., "MEMS switchable interdigital coplanar filter," IEEE Trans. Microwave Theory Tech., Vol. 51, 320-324, 2003. doi:10.1109/TMTT.2002.806517
8. Kraus, G. M., et al., "A widely tunable RF MEMS end coupled filter," IEEE MTTS Int. Microwave Symp. Dig., 429-432, 2004.
9. Karim, M. F., A. Q. Liu, A. Arokiaswami, and A. B. Yu, "A reconfigurable micromachined switching filter using periodic structures," IEEE Trans. Microwave Theory Tech., Vol. 55, 1154-1162, 2007. doi:10.1109/TMTT.2007.897670
10. Potrebić, M., D. Tošić, and A. Plazinić, "Reconfigurable multilayer dual-mode bandpass filter based on memristive switch," AEU - International Journal of Electronics and Communications, Vol. 97, 290-298, December 2018. doi:10.1016/j.aeue.2018.10.032
11. Ishida, H. and K. Araki, "Design and analysis of UWB bandpass filter with ring filter," IEEE MTT-S Int. Dig., 1307-1310, 2004.
12. Wong, S. W. and L. Zhu, "EBG-embedded multiple mode resonator for UWB bandpass filter with improve upper stop band performance," IEEE Wireless Component Lett., Vol. 17, 421-423, 2007. doi:10.1109/LMWC.2007.897788
13. Gozhenko, V., A. Przadka, and P. Hagn, "Multilayer LTCC bandpass filter design," IEEE 37th European Microwave Conference, 540-543, 2007.
14. Matsuge, K., S. Him, M. Ishida, T. Kitaham, and T. Yamamoto, "Full RF module with embedded filters for 2.4 GHz and 5 GHz dual band WLAN applications," IEEE MTT-S Int. Dig., 629-632, 2004.
15. Chan, K. Y., S. Fouladi, R. Ramer, and R. Mansour, "RF MEMS switchable interdigital bandpass filter," IEEE Wireless Component Lett., Vol. 22, 44-46, 2012. doi:10.1109/LMWC.2011.2176926
16. Brito, Z., I. Llamas-Garro, G. Navarro-Munoz, J. Perruisseau-Carrier, L. Pradell, F. Giacomozzi, and S. Colpo, "Precise frequency and bandwidth control of switchable microstrip bandpass filters using diode and microelectro-mechanical system technologies," IET Microwaves, Antennas & Propagation, Vol. 6, 713-719, 2012. doi:10.1049/iet-map.2012.0077
17. Lee, J., et al., "New bandstop filter circuit topology and its application to design of a bandstop-to-bandpass switchable filter," IEEE Trans. Microwave Theory Tech., Vol. 61, 1114-1123, 2013. doi:10.1109/TMTT.2012.2237036