1. Lucyszyn, S., I. D. Robertson, and A. H. Aghvami, "Negative group delay synthesiser," Electron. Lett., Vol. 29, No. 9, 798-800, Apr. 1993.
doi:10.1049/el:19930533
2. Wang, Z., Y. Cao, T. Shao, S. Fang, and Y. Liu, "A negative group delay microwave circuit based on signal interference techniques," IEEE Microw. Wireless Compon. Lett., Vol. 28, No. 4, 290-292, Apr. 2018.
doi:10.1109/LMWC.2018.2811254
3. Chaudhary, G., Y. Jeong, and J. Lim, "Microstrip line negative group delay lters for microwave circuits," IEEE Trans. Microw. Theory Techn., Vol. 62, No. 2, 234-243, Feb. 2014.
doi:10.1109/TMTT.2013.2295555
4. Wan, F., N. Li, B. Ravelo, J. Ge, and B. Li, "Time-domain experimentation of NGD active RC-network cell," IEEE Trans. Circuits Syst. II, Exp. Briefs, Vol. 66, No. 4, 562-566, Apr. 2019.
doi:10.1109/TCSII.2018.2870836
5. Wan, F., N. Li, B. Ravelo, and J. Ge, "O = O shape low-loss negative group delay microstrip circuit," IEEE Trans. Circuits Syst. II, Exp. Briefs, Vol. 67, No. 10, 1795-1799, Oct. 2020.
doi:10.1109/TCSII.2019.2955109
6. Wan, F., X. Miao, B. Ravelo, et al. "Design of multi-scale negative group delay circuit for sensors signal time-delay cancellation," IEEE Sens. J., Vol. 19, No. 19, 8951-8962, Oct. 2019.
doi:10.1109/JSEN.2019.2921834
7. Joeng, J., G. Chaudhary, and Y. Jeong, "Efficiency enhancement of cross cancellation power amplifier using negative group delay circuit," Microw. Opt. Techn. Let., Vol. 61, No. 7, 1673-1677, Nov. 2019.
doi:10.1002/mop.31765
8. Zhang, T. and T. Yang, "A novel fully reconfigurable non foster capacitance using distributed negative group delay networks," IEEE Access, Vol. 7, 92768-92777, Jul. 2019.
9. Zhu, M. and C. Wu, "Reconfigurable non-foster elements and squint-free beamforming networks using active transversal filter-based negative group delay circuit," IEEE Trans. Microw. Theory Techn., Vol. 70, No. 1, 222-231, Jan. 2022.
doi:10.1109/TMTT.2021.3074577
10. Ravelo, B., M. L. Roy, and Andre Perennec, "Application of negative group delay active circuits to the design of broadband and constant phase shifters," Microw. Opt. Techn. Lett., Vol. 50, No. 12, 3078-3080, Mar. 2008.
doi:10.1002/mop.23883
11. Ravelo, B., Andre Perennec, and M. L. Roy, "Synthesis of frequency-independent phase shifters using negative group delay active circuit," Int. J. RF Microwave Comput. Aided Eng., Vol. 21, No. 1, 17-24, Dec. 2010.
doi:10.1002/mmce.20482
12. Nebhen, J. and B. Ravelo, "Innovative microwave design of frequency-independent passive phase shifter with LCL-network and bandpass NGD circuit," Progress In Electromagnetics Research C, Vol. 109, 187-203, 2021.
doi:10.2528/PIERC21010201
13. Peng, Y. and L. Sun, "A Compact broadband phase shifter based on HMSIW evanescent mode," IEEE Microw. Wireless Compon. Lett., Vol. 31, No. 7, 857-860, Jul. 2021.
doi:10.1109/LMWC.2021.3077379
14. Lyu, Y. P., L. Zhu, and C. H. Cheng, "Wideband phase shifters with miniaturized size on multiple series and shunt resonators: proposal and synthetic design," IEEE Trans. Microw. Theory Techn., Vol. 68, No. 12, 5221-5234, Dec. 2020.
15. Bo, W. X., Y. Z. Shao, M. P. Yong, et al. "A universal reference line-based differential phase shifter structure with simple design formulas," IEEE Trans. Compon. Packag. Technol., Vol. 7, No. 1, 123-130, Dec. 2016.
16. Lyu, Y. P., L. Zhu, and C. H. Cheng, "Proposal and synthesis design of differential phase shifters with filtering function," IEEE Trans. Microw. Theory Techn., Vol. 65, No. 8, 2906-2917, Aug. 2017.
doi:10.1109/TMTT.2017.2673819
17. Guo, L., H. Zhu, and A. Abbosh, "Wideband phase shifter with wide phase range using parallel coupled lines and L-shaped networks," IEEE Microw. Wireless Compon. Lett., Vol. 26, No. 8, 592-594, Aug. 2016.
doi:10.1109/LMWC.2016.2587833
18. Lyu, Y. P., L. Zhu, and C. H. Cheng, "Design and analysis of Schiffman phase shifter under operation of its second phase period," IEEE Trans. Microw. Theory Techn., Vol. 66, No. 7, 3263-3269, Jul. 2018.
doi:10.1109/TMTT.2018.2829170
19. Yu, X., S. Sun, X. Jing, et al. "Design of ultraflat phase shifters using multiple quarter-wavelength short-ended stubs," IEEE Microw. Wireless Compon. Lett., Vol. 29, No. 4, 246-248, Apr. 2019.
doi:10.1109/LMWC.2019.2898780
20. Qiu, L. L., L. Zhu, and Y. P. Lyu, "Schiffman phase shifters with wide phase shift range under operation of first and second phase periods in a coupled line," IEEE Trans. Microw. Theory Techn., Vol. 68, No. 4, 1423-1430, Apr. 2020.
doi:10.1109/TMTT.2019.2953842
21. Aboul-Seoud, A. K., A. Hamed, and A. E.-D. S. Hafez, "Wideband tunable MEMS phase shifters for radar phased array antenna," 29th Nat. Radio Sci. Conf. (NRSC), 593-599, Apr. 2012.
doi:10.1109/NRSC.2012.6208570
22. Meng, Y., Z. Wang, S. Fang, T. Shao, H. Liu, and Z. Chen, "Group delay flatness and bandwidth enhancement of wideband negative group delay microwave circuit," Int. J. RF Microwave Comput. Aided Eng., Vol. 30, No. 12, 1-14, Sep. 2020.
doi:10.1002/mmce.22443
23. Wang, Z., Y. Meng, S. Fang, and H. Liu, "Wideband at negative group delay circuit with improved signal attenuation," IEEE Trans. Circuits Syst. II, Exp. Briefs, early access, Mar. 2022, DOI: 10.1109/TCSII.2022.3156537.