Li-based LTCC Dielectric Ceramic Of Material And Microwave Devices Research

In recent years,with the rapid development of mobile communications, the demand of performance on the communication base station is also rising.It provides new opportunities for used in communications base stations in the mid-high dielectric ceramic materials.A new direction for mid-high dielectric ceramic on microwave device miniaturization, integration and low-loss.There fore, researching of highly integrated and high stability LTCC dielectric ceramic material has a strong practical significance.Li2ZnTi3O8 is a permittivity of about 25 that has good microwave dielectric properties,high temperature stability dielectric ceramics, but its drawback that the sintering temperature is too high, sintering temperature is 1200℃, to make it ap ply to LTCC production must reduce its sintering temperature, meanwhile sinterin g does not significantly reduce its microwave performance at about 900℃. In or der to study Li2ZnTi3O8 at a low temperature sintering behavior and microwave dielectric properties, it uses three types of glass to burn them down, they are L BSCA, BBSZ and BBZ. Through the analysis of different doping amount of pha se composition, micro structure and microwave dielectric properties, to determine th e group of best performance, Li2ZnTi3O8+xwt% LBSCA(x=0.5-2.5),when x=1.5, the ceramics sintered at 900℃ for 3h exhibit the best performance microwave, its microwave properties:εr=23, Q*f=39762(f=8.010GHz),ρ=3.59g/cm3, τf=-13.75 ppm/℃. Using the same method described above were doped glass BBSZ and BBZ,further analysis of its role in burning down,when x=0.5-2.0, the ceramic material exhibits different properties. Respectively, when the doping x=0. 5wt% BBSZ, ceramics exhibit the best performance, the microwave dielectric pro perties:εr=25.1,Q*f=32475(f=7.805GHz),ρ=3.42g/cm3,τf=-14.8ppm/℃ When the doping x=0.5wt% BBZ,ceramics exhibit the best performance, the mic rowave dielectric properties:εr=20.01, Q*f=19673(f=8.370GHz), ρ=3.38g/cm3,τf=-15.4ppm/℃. Finally, in order to meet the resonance frequ ency temperature coefficient of the material, the use of TiO2 and CaTiO3 two ki nds positive temperature coefficient is adjusted, the choice of the three groups in the best performance Li2ZnTi3O8+1.5wt% LBSCA sintered at 900℃.Respectively After it that was added to 3.5wt% TiO2 and 2wt% CaTiO3, and its τf=+2.8ppm/℃,Q*f=27854 and τf=-3.2ppm/℃, Q*f=32048.At last, based on its own development of low loss microwave dielectric ceramic material Li2ZnTi3O8, design and simulation of a small strip line filter in the HFSS, the simulation by construction and electromagnetic simulation, and its simulation results: center frequency of 3.0GHz, bandwidth is 400MHz, in-band insertion loss is 2.3dB, standing wave is 1.3, the lower end of out-band rejection is 40dB, the higher of out-band rejection is 18dB.