| Summary: | 碩士 === 國立中央大學 === 電機工程學系 === 107 === The thesis presents practical designs for compact microwave diplexers and triplexers by using LC resonators. The circuits will be implemented with Low Temperature Co-fired Ceramic (LTCC) substrates to reach the requirement of compact size for the 5th Generation Mobile Communication Systems.
In multi-layered structures in LTCC substrates, vertical interdigitated capacitor, metal in metal (MIM) capacitor, and vertical helical inductor can be easily implemented. Therefore, compact multiplexers can be achieved, and transmission zeros near passbands can be introduced to enhance selectivity and isolation of the multiplexers.
The proposed diplexer is operated in two passbands: 698 – 2690MHz for 4G LTE and 3300 – 5850MHz for 5G Sub-6GHz. The measured characteristics in the lower band and upper band are given as follows. Low insertion losses are 0.62 dB and 0.76 dB. The rejection of out band are over 20 dB and 30 dB. The isolation are over 25 dB between two passbands. The return loss is over 18 dB in both passbands. The diplexer design occupies a volume of 2.5×2.0×0.65〖mm〗^3.
The proposed triplexer is operated in three passbands: 500 – 960MHz for 4G LTE low band, 1427 – 2690MHz for 4G LTE low band, and 3300 – 5850MHz for 5G Sub-6GHz. The measured characteristics in three passbands are described as follows. Low insertion loss is 0.65 dB, 0.88 dB and 1.06 dB in three passbands, respectively. The rejection of out band are over 20 dB, 30 dB and 20 dB. Isolation are over 22 dB between each two passband. Return losses are over 14 dB in all three passbands. The triplexer design occupies a volume of 2.5×2.0×0.65〖mm〗^3.
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