The Design Of 2492MHz Low Insertion Loss Saw Filter For Beidou Navigation Satellite System

With the rise of the global navigation satellite system and the vigorous construction of the BeiDou System in China,the related antennas,chips,modules and receivers are developing rapidly.The market demand for high-performance SAW filters for transmitting and receiving is huge.This paper focuses on the implementation of 2492MHz low loss SAW filter for the BeiDou signal receiver using 42°Y-X LiTaO₃ piezoelectric and Ladder structure design.On the basis of a large number of research on the principle,characteristics and parameters of surface acoustic wave,piezoelectric material and interdigital transducer,the preliminary design scheme and process direction are confirmed through the analysis of device performance requirements.After simulation,the structure which can satisfy the requirements of loss,bandwidth and suppression is selected from three connection modes,and the series and parallel resonators connection is further optimized to reduce the number of resonators.Finally,the structural parameters of the resonators are confirmed and the layout is obtained.In order to ensure the performance and reliability of the device,some production technologies of SAW devices are also optimized,such as the selection of black lithium tantalite as the substrate material,the use of lift-off to prepare IDT,the use of Al-Cu alloy instead of the conventional Al,and the thickening of the welding electrode area.The electrical performance test and reliability verification of the 2492MHz SAW filter are finally carried out.The result proves the correctness of the design scheme and process optimization.