声表面波低插入损耗滤波器的研制(Ⅱ)──横向耦合谐振滤波器

Design and performance of SAW low insertion loss filters(Ⅱ)Transversely-Coupled Resonator Filter

目前移动通信窄带低插损高阻带抑制的滤波器有极大需求，而横向模式耦合谐振滤波器是实现这些性能的最佳方案之一。在理论上，本文应用陈东培和Ｈａｒｔｍａｎｎ等提出的耦合模型理论模型对这种滤波器进行了分析设计，在实验上，以ＳＴ石英为基底材料，设计制作了１５２．５５ＭＨｚ频率的器件，器件性能接近目前国外已报道同类器件的水平，最低插损达２．７ｄＢ，阻带抑制约６０ｄＢ相对带宽０．５‰～０．７５‰。

Currently the mobile communication system has a great need of the filter with narrow bandwidth, low loss and high rejection. SAW transversely-coupled resonator filter (T CRF ) is t he optimum physical implementations of the filter above mentioned. In this papert we first analyzed theoretically TCRF using Coupling-of-Modes model presented by Chen & Hartmann et al. The experimental resultsof the filter fabricated on ST Quartz substrate is given. The device achieved favorable characteristics with an insertion loss of 2.7 dB, a sidelobe rejection of about 60 dB, a fractional bandwidth of about0.5 % and a very flat passband.