Implementation of a broadband Ruthroff-type transmission line transformer balun with a 1:2 step-up impedance transformation ratio is presented in this letter. The proposed Transmission Line Transformer (TLT) balun was investigated with broadside-coupled lines using three stacked microstrip lines. The proposed balun was formed by cascading one section of modified Ruthroff-type 2:1 unbalanced-to-unbalanced TLT with one section of Ruthroff-type 1:4 TLT balun in series. The achieved fractional bandwidth of the balun is 192.17% over the frequency range from 1.2 to 6.6 GHz, which covers the IEEE 802.11 a/b/g WLAN, WiMAX applications. The measured amplitude and phase imbalances are less than 1 dB and less than 4.51˚, respectively at this frequency range.
1. Niida, Y., M. Sato, T. Ohki, and N. Nakamura, "A 0.6-2.1-GHz wideband GaN high-power amplifier using transmission-line-transformer-based differential-mode combiner with second-harmonic suppression," IEEE Transactions on Microwave Theory and Techniques, Vol. 69, No. 3, 1675-1683, 2021. doi:10.1109/TMTT.2021.3053977
2. Wu, Y.-C., Y.-J. Hwang, C.-C. Chiong, B.-Z. Lu, and H. Wang, "An innovative joint-injection mixer with broadband IF and RF for advanced heterodyne receivers of millimeter-wave astronomy," IEEE Transactions on Microwave Theory and Techniques, Vol. 68, No. 12, 5408-5422, 2020. doi:10.1109/TMTT.2020.3017197
3. Lee, S., J. Park, and S. Hong, "Antenna switch embedded in transmission line transformers of differential PA and LNA," IEEE Microwave and Wireless Components Letters, Vol. 31, No. 3, 284-287, 2020. doi:10.1109/LMWC.2020.3044928
4. Yang, Y., Y. Wu, Z. Zhuang, M. Kong, W. Wang, and C. Wang, "An ultraminiaturized bandpass filtering Marchand balun chip with spiral coupled lines based on GaAs integrated passive device technology," Journal Title Abbreviation, Vol. 48, No. 9, 3067-3075, 2020.
5. Yang, G., R. Chen, and K. Wang, "A CMOS balun with common ground and artificial dielectric compensation achieving 79.5% fractional bandwidth and < 2◦ phase imbalance," 2020 IEEE/MTT-S International Microwave Symposium (IMS), 1319-1322, 2020. doi:10.1109/IMS30576.2020.9223981
6. Guanella, G., "New method of impedance matching in radio-frequency circuits," The Brown Boveri Review, Vol. 31, 125-127, 1944.
8. Mack, R. A. and J. Sevick, Sevick's Transmission Line Transformers: Theory and Practice, IET, 2014. doi:10.1049/SBEW513E
9. Rotholz, E., "Transmission-line transformers," IEEE Transactions on Microwave Theory and Techniques, Vol. 29, No. 4, 327-331, 1981. doi:10.1109/TMTT.1981.1130352
10. Chung, H.-Y., H.-K. Chiou, Y.-C. Hsu, T.-Y. Yang, and C.-L. Chang, "Design of step-down broadband and low-loss Ruthroff-type baluns using IPD technology," IEEE Transactions on Components, Packaging and Manufacturing Technology, Vol. 4, No. 6, 967-974, 2014. doi:10.1109/TCPMT.2014.2311662
11. Chiou, H.-K. and H.-Y. Chung, "2.5-7 GHz single balanced mixer with integrated Ruthroff-type balun in 0.18 μm CMOS technology," Electronics Letters, Vol. 49, No. 7, 474-475, 2013. doi:10.1049/el.2012.4091
12. Gomez-Jimenez, P., P. Otero, and E. Marquez-Segura, "Analysis and design procedure of transmission-line transformers," IEEE Transactions on Microwave Theory and Techniques, Vol. 56, No. 1, 163-171, 2008. doi:10.1109/TMTT.2007.912246
13. Grebennikov, A., "Power combiners, impedance transformers and directional couplers," High Frequency Electronics, Vol. 6, No. 12, 20-38, 2007.
14. Trask, C., "Transmission line transformers: Theory design and applications," High Frequency Electronics, Vol. 4, 46-53, 2005.
15. Burasa, P., T. Djerafi, N. G. Constantin, K. Wu, and , "On-chip dual-band rectangular slot antenna for single-chip millimeter-wave identification tag in standard CMOS technology," IEEE Transactions on Antennas and Propagation, Vol. 65, No. 8, 3858-3868, 2017. doi:10.1109/TAP.2017.2710215
16. Sobrany, R. F. and I. D. Robertson, "Ruthroff transmission line transformers using multilayer technology," 33rd European Microwave Conference Proceedings (IEEE Cat. No. 03EX723C), Vol. 2, 559-562, 2003. doi:10.1109/EUMA.2003.341014
17. Sahan, N., M. E. Inal, S. Demir, and C. Toker, "High-power 20-100-MHz linear and efficient power-amplifier design," IEEE Transactions on Microwave Theory and Techniques, Vol. 56, No. 9, 2032-2039, 2008. doi:10.1109/TMTT.2008.2002238
18. Liu, S.-P., "Planar transmission line transformer using coupled microstrip lines," 1998 IEEE MTT-S International Microwave Symposium Digest (Cat. No. 98CH36192), Vol. 2, 789-792, 1998.
19. Huang, C.-H., T.-S. Horng, C.-C. Wang, C.-T. Chiu, and C.-P. Hung, "Optimum design of transformer-type Marchand balun using scalable integrated passive device technology," IEEE Trans. on Components, Packaging and Manufacturing Technology, Vol. 2, No. 8, 1370-1377, 2011. doi:10.1109/TCPMT.2011.2171514
20. Liu, X., J. Zhou, Z. Deng, and X. Luo, "Compact wideband Marchand balun with amplitude and phase compensation shield," 2019 IEEE MTT-S International Microwave Symposium (IMS), 448-451, 2019. doi:10.1109/MWSYM.2019.8700816
21. Ahn, H.-R. and M. M. Tentzeris, "A novel compact isolation circuit suitable for ultracompact and wideband Marchand baluns," IEEE Transactions on Circuits and Systems II: Express Briefs, Vol. 67, No. 10, 2299-2303, 2019. doi:10.1109/TCSII.2019.2960005
22. Wang, Y. and J.-C. Lee, "A miniaturized Marchand balun model with short-end and capacitive feeding," IEEE Access, Vol. 6, 26653-26659, 2018. doi:10.1109/ACCESS.2018.2834948