A Negative Group delay (NGD) triple passband filter with a lossy Meander Step Impedance Resonator (MSIR) is introduced in this article. The size miniaturization technique by increasing the number of meander turns is presented. In the process of filter design, the calculation of the total inductance value of the meander section is discussed in a simplified way. At the same time, the electrical and physical lengths of each section of meander resonator are calculated. The proposed filter has three passbands at 2.4, 5.0, and 7.4 GHz. The Group Delay (GD) in the three pass bands is -2.5 ns, -2.1 ns, and -2.0 ns, respectively. The more the number of meander turns is, the more the NGD will be. The proposed design is well equipped to be used in feed-forward and feed-back power amplifier applications. The frequency response exhibits satisfactory Return Losses (RLs) of -24, -25, and -22 dB at these three passbands. Four Transmission Zeros are generated at 3.35, 3.98, 6.2, and 8.31 GHz using an absorptive Folded SIR (FSIR) structure which improve the stopband performance. The overall dimension of the filter is (20.7 x 12) mm = (0.16 x 0.09)λg.
2. Chaudhary, G. and Y. Jeong, "Negative group delay phenomenon analysis using finite unloaded quality factor resonators," Progress In Electromagnetics Research, Vol. 156, 55-62, 2016.
3. Liu, G. and J. Xu, "Compact transmission-type negative group delay circuit with low attenuation," Electron. Letters, Vol. 53, No. 7, 476-478, 2017.
4. Wang, Z., Y. Cao, T. Shao, S. Fang, and Y. Liu, "A negative group delay microwave circuit based on signal interference techniques," IEEE Microwave Wireless Compon. Lett., Vol. 28, No. 4, 290-292, 2018.
5. Choi, H., Y. Jeong, C. D. Kim, and J. S. Kenney, "Efficiency enhancement of feed forward amplifiers by employing a negative group-delay circuit," IEEE Trans. Microwave Theory Tech., Vol. 58, No. 5, 1116-1125, 2010.
6. Qiu, L., L. Wu, W. Yin, and J. Mao, "Absorptive band stop filter with prescribed negative group delay and bandwidth," IEEE Microwave Wireless Compon. Lett., Vol. 27, No. 7, 639-641, 2017.
7. Gomez-Garcia, R., J.-M. Munoz-Ferreras, and D. Psychogiou, "Adaptive multi-band negative-group-delay RF circuits with low reflection," IEEE Transactions on Circuits and Systems, Vol. 68, No. 5, May 2021.
8. Joeng, J., G. Chaudhary, and Y. Jeong, "Efficiency enhancement of cross cancellation power amplifier using negative group delay circuit," Microw. Opt. Technol. Lett., Vol. 61, No. 7, 1673-1677, 2019.
9. Yang, G., Q. Liu, S. Liu, and Y. Chang, "A compact wideband filtering power divider," Progress In Electromagnetics Research Letters, Vol. 81, 71-76, 2019.
10. Du, R.-N., Z.-B. Weng, and C. Zhang, "A miniaturized filtering 3-dB branch-line hybrid coupler with wide suppression band," Progress In Electromagnetics Research Letters, Vol. 73, 83-89, 2018.
11. Wang, Y. X., Y. L. Chen, W. H. Zou, W. C. Yang, and J. Zen, "Dual-band bandpass filter design using stub-loaded Hairpin resonator and meandering uniform impedance resonator," Progress In Electromagnetics Research Letters, Vol. 95, 147-153, 2021.
12. Wang, Z., Z. Fu, C. Li, S.-J. Fang, and H. Liu, "A compact negative-group-delay microstrip bandpass filter," Progress In Electromagnetics Research Letters, Vol. 90, 45-51, 2020.
13. Xiao, J. and Q. Wang, "Individually controllable tri-band negative group delay circuit using defected microstrip structure," Cross Strait Quad-Regional Radio Sci. Wirel. Technol. Conf., 1-3, Taiyuan, China, 2019.
14. Meng, Y., Z. Wang, S.-J. Fang, and H. Liu, "A tri-band negative group delay circuit for multiband wireless applications," Progress In Electromagnetics Research C, Vol. 108, 159-169, 2021.
15. Grover, F. W., Inductance Calculations, Working Formulas and Tables, D. van Nostrand Company, Inc., Princeton, 1946; reprinted by Dover Publications, New York, 1954.
16. Makimoto, M. and S. Yamashita, Microwave Resonators and Filters for Wireless Communication, Springer, 2003.
17. Stojanovic, G., L. Zivanov, and M. Damjanovic, "Compact form of expressions for inductance calculation of meander inductors," Serbian Journal of Electrical Engineering, Vol. 1, No. 3, 57-68, November 2004.