| High Selectivity Coupled Line Impedance Transformer with Second Harmonic Suppression |
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Phirun Kim, Junsik Park, Junhyung Jeong, Seungho Jeong, Girdhari Chaudhary, Yongchae Jeong |
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Division of Electronics and Information Engineering, IT Convergence Research Center, Chonbuk National University |
Correspondence:
Yongchae Jeong,Email: ycjeong@jbnu.ac.kr
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| Abstract |
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This paper presents a design of an impedance transformer (IT) with high frequency selectivity characteristics. The frequency selectivity can be controlled by even- and odd-mode impedance of a shunt coupled transmission line (TL). For experimental validation, a 50- to $20-{Omega}$ IT was implemented at a center frequency ($f_0$) of 2.6 GHz for the long-term evolution signal. The measured results were in good agreement with the simulations, showing a return loss higher than 19 dB over a passband bandwidth of 0.63 GHz (2.28-2.91 GHz) and good sharp frequency selectivity characteristic near to the passband. The series coupled TL provides a transmission zero at 5.75 GHz, whereas the shunt coupled TL provides three transmission zeros located at 2 GHz, 3.1 GHz, and 7.14 GHz. |
| Key words:
Coupled Line, Impedance Transformer, Selectivity, Transmission Zeros |
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