Study Of Microwave Passive Miniaturization Based On LTCC Technology

With the development of millimeter-wave integrated circuits, smaller, lighter and more efficient passive circuits have become popular. As a result, the design and fabrication technology of passive devices face more challenging requirements. Traditional fabrication technology is less able to meet microwave system’s requirements for miniaturization.Temperature Co-fired Ceramic,(LTCC) technology outstands as solution for more compact circuits. LTCC applies multilayer circuits and three-dimension layout, making more efficient and smaller passive circuits possible. The main purpose of this thesis is to making the miniaturized passive circuit using LTCC technology.This paper first analyses the advantages and disadvantages of LTCC technology in the passive circuit’s application. As fabrication is an important part of LTCC technology, the paper discusses the fabrication technology and design specifications of LTCC in details and elaborates the basic principle of the filter. The design of miniaturized passive circuits is as follows.In this study, a compact low-pass filter is designed based on LTCC characteristics, process and design standard. The frequency band is from DC to 4.0GHz. The insertion loss is less than1.5dB. The band rejection is greater than 17 dB. The size of the filter is 3.9mm×2.5mm×0.85 mm.The dielectric material is Dupont951 PT, whose dielectric constant is 7.8 and loss tangent is 0.002.Two SIW based multilayer filters are designed and simulated in this study. The first filter employs microstrip line as the input and the output ports. The pass band is from 26 to 30 GHz. Its central frequency is 28 GHz. The return loss at 28 GHz is greater than 25 dB, and the insertion loss is less than 0.1dB. The size of the filter is 7mm×3.5mm×1mm. The second filter works at W-band. Its central frequency is 93 GHz, and its bandwidth is greater than 4GHz. The return loss at 93 GHz is greater than 32 dB, and the insertion loss is less than 2dB.A 30-40 GHz LTCC miniaturized patch antenna is designed at last. S11 of the antenna is less than-10 dB in-band. The whole structure has 10 layers of LTCC substrate. Each layer of the substrate is 0.094 mm thick. The bottom layer is slot coupled fed and the feeding structure is 50Ω microstrip line.