The Design And Modeling Of LTCC Lump-element Duplexer

This paper is based on the theories of microwave filter and duplexer, mainly introduced the design and modeling of LTCC lump-element duplexer. In order to reduce the circuit's complexity and save the area, the matching network is removed by the filter complementary method. This paper specified how to realize lump-element components in LTCC technics and the method of changing the band pass filter's structure to accommodate LTCC technology. In the out band, transmission zeros are introduced to increase the attenuation and eliminated the matching network of uncomplementary citcuit by analysising the input susceptance. Moreover the size of duplexer is reduced by adopting different structures. In this paper, two duplexers have been designed with different structures and types. Their center frequencies are both 1.61GHz and 2.49GHz. Their sizes are separately 9mm×6mm×1.5mm and 4.6mm×3.8mm×1.35mm. The three dimensional models of the two duplexers are simulated with Ansoft HFSS software, the insertion losses of the first duplexer are 0.88dB and 1.31dB, the attenuations of 1.61GHz and 2.49GHz are separately 46.49dB and 57.84dB; the insertion losses of the second duplexer are 0.66dB and 1.07dB, the attenuations of 1.61GHz and 2.49GHz are separately 25.34dB and 27.7dB. The two duplexers both reach the requirements of design.