A Miniaturized Diplexer with Low Insertion Loss and High Isolation Based on LTCC

This paper introduces a low-temperature co-fired ceramic (LTCC) diplexer for 1.575/2.45/5.4GHz applications. Exceptional simulation results with low insertion loss are achieved by the LTCC diplexer through the implementation of a complementary structure that combines low-pass and high-pass filters. Specifically, it achieves insertion losses below 0.66dB, 0.72dB, and 0.5dB for applications at 1.575GHz, 2.45GHz, and 5.4GHz respectively. The size of the presented LTCC diplexer is
$\mathbf{1.6}\times \mathbf{0.8}\times \mathbf{0.69}\ \mathbf{mm}^{\mathbf{3}}$
, which is significantly more compact when compared to previously reported LTCC diplexers. The LTCC circuit model and 3-D model are shown. The simulation proves modes are reliable.