Design And Implementation Of Miniaturized Filter Based On LTCC Technology

As more than 50 communication bands are added to 5G communications,the number and design difficulty of RF front-end components for consumer electronics are greatly increased.High-end filters are the fastest growing segment of RF front-end.High-end filters can be divided into LTCC,SAW,BAW and other types.Compared with SAW and BAW filters,LTCC filters have the advantages of wider bandwidth,higher frequency band,and low pass and high pass.High-end filters have up to 100 billion market share,but more than 90% of the market is monopolized by Japan and the United States,domestic manufacturers of manufacturing equipment,materials and other mainly rely on foreign imports.In addition,domestic LTCC filter products are not small enough in size,packaging pins are not standardized,performance is difficult to match foreign products,so there is a large space for domestic replacement.Therefore,it is of great significance to develop LTCC passive components with the same volume and similar performance as foreign products and with standard pins.In this paper,six filters are designed based on LTCC technology.They are mainly used in the new frequency band of mobile communication and wifi.They have smaller volume and better performance.The main research contents of this paper are as follows:A 1.6mm×0.8mm×0.5mm low-pass filter is designed.Due to the reasonable prototype circuit and component layout,the miniaturization of the low-pass filter is realized.Because the equivalent circuit model is extracted,the characteristics of capacitance and inductance are not changed in a wide frequency band.Two filters,N77(2.0mm×1.25mm×0.7mm)and N79(1.0mm×0.5mm×0.38mm),are designed.The principle of cross-coupling to generate transmission zero is applied.In order to realize the miniaturization of the filter,the medium with high dielectric constant is adopted.A high-pass filter with the size of 2.0mm×1.25mm×0.95 mm was designed.The UIR(uniform characteristic impedance resonance structure)was used to design the position of input and output tap to reduce the influence on the return loss,and the high-pass filter was flat with small insertion loss.Finally,a 1.6mm×0.8mm×0.665 mm band-pass filter suitable for B34 and B39 and a1.6mm×0.8mm×0.6mm 5G?wifi band-pass filter are designed.In addition to designing a reasonable ADS prototype circuit,Moreover,the parasitic parameters of the components and the additional transmission zeros generated by the coupling of the components are carefully used in the design so that higher stopband rejection can be achieved without increasing the volume.