Design And Research Of Ultra-wideband Filter Based On LTCC Technology

The 5G era is coming,the communication equipment has put forward more stringent design standards for all kinds of electronic devices.The low temperature co-firing ceramic(LTCC)technology using 3D integration technology,can realize the miniaturization of electronic devices,low cost and high performance.Ultra-wide band filter plays an important role in UWB systems as the very important part of passive devices.UWB filters based on LTCC technology are widely used in weapons,medical,satellite navigation and other fields.How to make the LTCC UWB filter with wider stop band,lower loss and smaller size is the focus of this thesis.In this dissertation,the design of ultra-wideband filter based on LTCC technology is studied.Theoretical analysis and research on the resonant unit of loaded grounding capacitor,dual-mode resonant structure and open-ended coupling line structure are carried out.Four high performance LTCC ultra-wideband filters have been successfully implemented.The main research results are as follows:(1)A wide impedance band resonant unit is realized by using the loaded grounding capacitor.According to the coupling characteristics between resonant unit and the characteristics of all levels of resonant units,a four level high performance UWB filter with the size of 4.4mm × 2mm × 1.2mm is designed.On this basis,a five stage ultra wideband filter with wide resistance band and high suppression is designed.The size is only 4.4mm× 2.2mm ×1.2mm.(2)Analyze the dual-mode resonance element by using the odd-even mode analysis method,and then the dual-mode UWB filter is designed by using the double end open resonator with the center loading short-circuit stub.Finally a dual-mode resonant UWB filter based on LTCC technology with high performance and micro-size has been designed successfully,with the passband frequency of 4GHz?8.4GHz and the size of 4.4mm × 2.6mm × 1.1mm.(3)Based on the theory of coupling line,the filter characteristics of the open coupling line at both ends are analyzed in detail.With the advantages of tight layout of LTCC,a folded wide-brimmed coupling line with strong coupling is designed as the basic unit of an ultra-wideband filter.Based on this,the three cascade coupling line structure has been designed.The coupling line UWB filter loaded by short stub is designed as the innovation based on this structure,with the passband frequency of 3.8GHz?11 GHz and the size of 4.5mm×3mm×1.5mm.