A N77 band bandpass filter for 5G applications using LTCC technology with wide upper stopband
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Bowei Liu
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Gang Shi
Abstract
A bandpass filter (BPF) designed for the 5G N77 band using low-temperature co-fired ceramic (LTCC) technology is presented in this paper. This proposed BPF incorporates a pair of hook-shaped microstrip feeding lines (HSMFLs) on the top layer and a T-junction resonator on the second layer. In order to realize a wider upper stopband, the HSMFL is composed of a stepped-impedance variation microstrip line (SIVML) and a folded microstrip line with enhanced coupling effect at the end. With a compact structure measuring 26.85 × 12.68 × 0.20 mm3, which equates to 0.689 × 0.325 × 0.005 λ g 3, the design achieves an exceptional performance profile. The proposed BPF demonstrates superior performance with an out-of-band suppression higher than 20 dB up to 3.35 f 0 , while maintaining low in-band insertion loss (IL) under 0.3 dB. The proposed BPF offers significant potential for 5G mobile communications due to its wide upper stopband, exceptional out-of-band suppression capability, low in-band IL, simple design, and compact structure.
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Research ethics: Not applicable.
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Informed consent: Not applicable.
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Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.
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Use of Large Language Models, AI and Machine Learning Tools: None declared.
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Conflict of interest: The author states no conflict of interest.
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Research funding: None declared.
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Data availability: All the data are available in the manuscript.
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