volume | PIER Journals

Abstract

In this paper, a compact negative-group-delay (NGD) microstrip bandpass filter is proposed. The NGD characteristic is achieved by coupling a resistor-loaded microstrip line to a square open-loop resonator. To improve the selectivity, the square open-loop resonator is loaded with an open-circuited stub for realizing two transmission zeros (TZs) in the upper stopband. To verify the proposed method, an NGD microstrip bandpass filter with a size of 0.58λ_g × 0.35λ_g is designed and fabricated. From the measured results, the NGD time of -1.08 ns at the center frequency of 1.995 GHz is obtained with the NGD bandwidth of 34 MHz (1.977-2.011 GHz), in which the insertion loss is less than 7.5 dB, and the return loss is greater than 20 dB. Furthermore, three TZs at 1.520, 2.495, and 2.735 GHz are achieved with good stopband attenuation.

1. Liu, F. and M. Qun, "A new compact UWB bandpass filter with quad notched characteristics," Progress In Electromagnetics Research Letters, Vol. 88, 83-88, 2020.
doi:10.2528/PIERL19090505 Google Scholar

2. 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. Google Scholar

3. 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.
doi:10.2528/PIERL17111406 Google Scholar

4. Ravelo, B., "Theory of coupled line coupler-based negative group delay microwave circuit," IEEE Trans. Microwave Theory Tech., Vol. 64, No. 11, 3604-3611, 2016.
doi:10.1109/TMTT.2016.2604316 Google Scholar

5. 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.
doi:10.2528/PIER16041111 Google Scholar

6. Liu, G. and J. Xu, "Compact transmission-type negative group delay circuit with low attenuation," Electron. Lett., Vol. 53, No. 7, 476-478, 2017.
doi:10.1049/el.2017.0328 Google Scholar

7. 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.
doi:10.1109/LMWC.2018.2811254 Google Scholar

8. Noto, H., K. Yamauchi, M. Nakayama, and Y. Isota, "Negative group delay circuit for feed-forward amplifier," IEEE MTT-S Int. Microwave Symp. Dig., 1103-1106, Honolulu, HI, USA, 2007. Google Scholar

9. Ahn, K. P., R. Ishikawa, and K. Honjo, "Group delay equalized UWB InGaP/GaAs HBT MMIC amplifier using negative group delay circuits," IEEE Trans. Microwave Theory Tech., Vol. 57, No. 9, 2139-2147, 2009.
doi:10.1109/TMTT.2009.2027082 Google Scholar

10. 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.
doi:10.1002/mop.31765 Google Scholar

11. Mirzaei, H. and G. V. Eleftheriades, "Realizing non-Foster reactive elements using negative-group-delay networks," IEEE Trans. Microwave Theory Tech., Vol. 61, No. 12, 4322-4332, 2013.
doi:10.1109/TMTT.2013.2281967 Google Scholar

12. Mirzaei, H. and G. V. Eleftheriades, "Arbitrary-angle squint-free beamforming in series-fed antenna arrays using non-foster elements synthesized by negative-group-delay networks," IEEE Trans. Antennas Propag., Vol. 63, No. 5, 1997-2010, 2015.
doi:10.1109/TAP.2015.2408364 Google Scholar

13. Choi, H., Y. Jeong, C. D. Kim, and J. S. Kenney, "Efficiency enhancement of feedforward amplifiers by employing a negative group-delay circuit," IEEE Trans. Microwave Theory Tech., Vol. 58, No. 5, 1116-1125, 2010.
doi:10.1109/TMTT.2010.2045576 Google Scholar

14. Choi, H., Y. Jeong, C. D. Kim, and J. S. Kenney, "Bandwidth enhancement of an analog feed-back amplifier by employing a negative group delay circuit," Progress In Electromagnetics Research, Vol. 105, 253-272, 2010.
doi:10.2528/PIER10041808 Google Scholar

15. Chaudhary, G., Y. Jeong, and J. Lim, "Microstrip line negative group delay filters for microwave circuits," IEEE Trans. Microwave Theory Tech., Vol. 62, No. 2, 234-243, 2014.
doi:10.1109/TMTT.2013.2295555 Google Scholar

16. Qiu, L., L. Wu, W. Yin, and J. Mao, "Absorptive bandstop filter with prescribed negative group delay and bandwidth," IEEE Microwave Wireless Compon. Lett., Vol. 27, No. 7, 639-641, 2017.
doi:10.1109/LMWC.2017.2711572 Google Scholar

Dr. Zhongbao Wang

Dr. Zheng Fu

Dr. Chengze Li

Prof. Shao-Jun Fang

Professor Hongmei Liu