Design of miniaturized tunable band - pass filter based on LTCC process

A miniaturized second-oder Inductive Coupling band-pass filter based on low temperature co-firing ceramic (LTCC) technology was designed in this paper, The coupling effect between the two resonators is used to further reduce the size of the device. On the basis of this filter, the simulation of the surface paste varactor diode and then achieve the center frequency adjustable. The filter model is established and simulated in the three-dimensional electromagnetic field simulation software HFSS. The results show that the center frequency of the filter can be continuously changed in the range of 1.05GHz ~ 1.23GHz, the insertion loss is kept below 1dB, the return loss is always greater than 15dB, the out-of-band suppression is better than 45dB at 2fo, the overall size is 6.5mm × 4mm × 0.9mm.