Research And Design Of Band - Pass Filter Based On 3D Integration

With the rapid development of wireless communications industry and national sophisticated electronic systems, the design of RF devices especially filters request higher requirements, high rejection and miniaturization are two major challenges that exist in the current design. Three-dimensional integrated structure based on LTCC technology can reduce the size of the device effectively, and more flexibility in the circuit design, which makes it become a hotspot in the research of the current industry.The core research in this paper is high rejection band-pass filter, the exploration and research of the band-pass filter design theory which is based on LTCC technology are discussed. With the electromagnetic simulation software ADS and HFSS to make a thorough analysis. Particularly, considering the actual engineering demands, three good performance band-pass filters which applied in military communications systems are given, the design theory is proved correct because test results meet with the simulation results very well.The main work of this paper is as follows:Semi-lumped band-pass filter are consisted of traditional inductance and capacitance, so there exists spatial coupling between resonators. As a result, it reduces the size of device when works at low frequencies. Based on the study of a resonator and according to filter design theory, the circuit topology and three-dimensional structure of a 170MHz band-pass filter are given in this paper. Particularly, a three-dimensional model of two cascaded band-pass filter is built and then analyze its strengths and weaknesses, which the rejection of it’s stop-band is greatly improved.Distributed band-pass filter use the traditional three-strip line as a resonant cell, first, it gives the basic theoretical introduction of strip-line resonators, and then describes it’s mathematical model and structural characteristics. Finally, a six band-pass filter is designed by electromagnetic simulation software, which have two zeros in high and low stop-band by using the theory of transmission zeros. The structure of this filter is simple and performance is excellent, especially in stop-band rejection and miniaturization it has obvious advantages.In this paper, the band-pass filters which based on three dimensional integrated have good performance and integration, it meets the application requirements very well, and the designed filters are fabricated using the LTCC process and have been used in system.