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群型单向换能器(Group-type unidirectional transducer简称G-UDT)低损耗声表面波(SAW)滤波器,最近几年,在国外受到广泛的重视,在国内也仍是急待解决的研究课题.本文首先简述了低损耗SAW滤波器的由来,比较了几种实现低损耗滤波器的方法.对G-UDT SAW滤波器进行了详细的分析;叙述了脉冲模式滤波器综合设计程序.根据本文分析和设计方法,对f_0为60MHz和10.7MHz两种滤波器进行实验,带宽分别为3%和5%.利用Y_128°-X传播LiNbO_3,用合适的加权换能器,合理的工艺和移相元件,得到6dB的插入损耗,通带波动很小,阻带抑制在40dB左右.理论与实验基本相近.
Group-type unidirectional transducers (G-UDTs) Low-loss SAW (SAW) filters have received widespread attention in foreign countries in recent years and are still in urgent need of solution in China Task.This paper firstly introduces the origin of low loss SAW filter and compares several methods to realize low loss filter.The G-UDT SAW filter is analyzed in detail, and the comprehensive design procedure of pulse mode filter is described. According to the analysis and design method of this paper, two kinds of filters with f_0 of 60MHz and 10.7MHz are experimented with bandwidths of 3% and 5%, respectively.It propagates LiNbO_3 with Y_128 ° -X, with appropriate weighted transducers, reasonable process and Phase-shifting element, get 6dB insertion loss, the passband fluctuation is very small, the stopband is suppressed at about 40dB.Theories and experiments are basically similar.