The Design And Research Of Laminated Chip Splitters Based On LTCC Technology

Co₂Z, a type of ferrite material with high permeability, high cut-off frequency, lowloss and superior temperature stability working at high frequencies, is an ideal substratematerial for high frequency chip devices. Co₂Z type Barium-Strontium ferrite, alsoCo₂Z doped with Sr2+, which performs much better at high frequencies than normalCo₂Z, is the focus of this paper. First, the impact of preparation by solid phase method isdiscussed. Samples are prepared at various points in a range of Pre-sinteringtemperature and sintering temperature in different atmospheres, and the phasecomposition, microstructure, and magnetic property of them are analyzed. Theexperiment shows that the most proper preparation environment is at pre-sinteringtemperature1270℃and sintering temperature1240℃in oxygen. Afterwards, thetechnique of low-temperature sintering of Co₂Z type Barium-Strontium ferrite is studied,for its application combined with the proven packaging technology. Properties of thesamples prepared by chemical method and solid phase oxide doping method arerespectively tested and analyzed. The study indicates that the sintering temperaturecannot be lowered down to900℃by applying chemical method only, whilst lowmelting point oxide doping method can effectively reduce the sintering temperature ofthe material. The pre-sintered samples doped with4%Bi2O3,2%CuO and1%V2O5canbe sintered at900℃and show excellent properties, e.g. relatively pure phase, equallysmall crystalline grain and good initial permeability at approximately3.5. Finally, ahigh frequency chip inductor and a chip Wilkinson halving power divider are designedbased on this material. The inductor and power divider are simulated and analyzed byAnsoft HFSS （High Frequency Structure Simulator）. The results prove that the inductormade of this material contains higher inductance than the one made of ceramic material.A single-turn coil of this inductor contains7.5nH inductance. The power divider showsgood properties, specifically insertion loss lower than3.5dB, isolation and return losshigher than20dB, at a frequency range of200MHz bandwidth centered at1GHz, whichconfirms the theoretical practicability of Co₂Z type Barium-Strontium ferrite designedchip Wilkinson halving power divider.