一种实现高带外抑制声表面波滤波器结构

为了获得高的带外抑制，我们设计了一种单相单向换能器与镜像阻抗连结换能器结合的滤波器结构。该结构由双通道组成，每通道上由一个电级宽度控制单相单向端变迹加权换能器和一个抽指加权换能器组成，它具有带外抑制高、插损小、体积小和制作容易等优点，克服了常规滤波器级联带来的插损大，难匹配的问题。最后给出了我们制作在１２７．８６°Ｙ－ＸＬｉＮｂＯ＿３基片上的高带外抑制声表面波滤波器结果，其中心频率为７０ＭＨｚ，带宽为１．５ＭＨｚ，带外抑制大于７０ｄＢ，插损小于１３ｄＢ，芯片尺寸小于５ｍｍ×１０ｍｍ。     

900MHz高频低损耗声表面波滤波器

介绍了在３６°ＹＸＬｉＴａＯ＿３基片上采用镜像阻抗连接换能器结构研究制作出９００ＭＨｚ高频低损耗声表面波滤波器，插入损耗小于５ｄＢ、带外抑制优于５０ｄＢ。     

改进低损耗SAW滤波器用换能器的几种新结构

最近,报道了多种改进低损耗SAW滤波器用换能器的新结构.改进的换能器包括单相单向换能器(SPUDT)、群型单向换能器(GTUDT)、群型单相单向换能器,(GSPUDT)、新型单相单向换能器(MEMUDT、SUDT、RSUDT)以及低损耗SAW-TV-IF滤波器用的故意不完全的(intentionally inperfeet)单向换能器(HUT)等.本文叙述上述各种换能器结构的工作原理和结构设计.并介绍了几种实验性的低损耗SAW滤波器的主要性能.     

一种宽带低损耗声表面波滤波器

阐述了一种利用纵向耦合双模制作宽带低损耗声表面波滤波器的方法，给出了理论计算方法和计算机模拟结果，最后给出了制作中心频率为４５３ＭＨｚ的声表面波滤波器实验结果，插入损耗为１．９ｄＢ，１ｄＢ带宽为６．６６ＭＨｚ，远端带外抑制大于４５ｄＢ。     

镜像阻抗连接叉指换能器制作低损耗声表面波滤波器浅探

介绍了镜像阻抗连接叉指换能器制作低损耗声表面波滤波器的基本原理，给出了研制的在同一种基片上采用不同的镜像阻抗连接叉指换能器制作的不同带宽的低损耗声表面波滤波器，并且可从结果中看到带内波动≤０．３ｄＢ。     

一种采用NSPUDT结构的新型滤波器

利用自然单相单向换能器,可以制作低损耗的声表面波器件。因自然单相单向换能器基片的单向性依赖于晶体的取向,用常规的单指结构就可以获得单向性。为了得到低损耗的滤波器,在相对方向上的接受换能器也设计成单向传输。文中介绍了一种使自然单相单向换能器基片单向性反向传输的新型滤波器结构,并给出采用这种结构设计制作 的声表面波滤波器的结果。     

采用EWC单相单向换能器的SAW滤波器组

采用带旁瓣的ＥＷＣ单相单向换能器技术，研制中等相对带宽（５．６％～７．１％）和具有好矩形度的声表面波滤波器组。该滤波器组用于通信电子对抗，工作频率为３０～４０ＭＨｚ，各信道的矩形系数为１．６，信道插入损耗１５ｄＢ，滤波器组输入端口的驻波系数小于１．５。     

低损耗高阻带抑制声表面波滤波器

为了提高雷达信号的接收灵敏度,提出一种低损耗高性能的单相单向换能器,其设计采用了电极宽度控制来实现。发射和接收叉指换能器分别选取适当的加权函数,能得到更低的旁瓣电平。设计制作了中心频率67 MHz,3 dB带宽1 MHz,单向性为21 dB,插损3.8 dB,阻带抑制大于45 dB的低损耗高阻带抑制声表面波滤波器。     

声表面波大带宽滤波器的设计

报道在Ｙ旋１２７．８６°Ｘ传ＬｉＮｂＯ＿３基片上采用１／８λ＿０，５／８λ＿０结构的切指加权换能器的声表面波滤波器，成功地研制了中心频率为４０ＭＨｚ，３ｄＢ带宽为２０ＭＨｚ，矩形系数（Δｆ＿４０ｄＢ／Δｆ＿３ｄＢ）为１．４８，带内波动＜１．２ｄＢ，带外抑制＞４０ｄＢ．插入损耗＜３８ｄＢ，相对带宽（Δｆ＿－３ｄＢ／ｆ＿０）大于５０％的滤波器。     

高频低损耗声表面波滤波器研制

回顾了低损耗声表面波滤波器的主要设计方法，介绍了镜像阻抗连接换能器结构中调整滤波器带宽的设计技术，给出了在９６０ＭＨｚ高频下的两种试验结果，相对带宽分别为１％和２％，插入损耗小于５ｄＢ，阻带抑制优于５０ｄＢ。     

用于频率合成的声表面波滤波器

介绍了几组用于扩频系统的声表面波滤波器的设计、制作和实验结果.器件频率为95～350MHz.插入损耗为9～24dB.阻带抑制优于45dB.     

Optimization of unidirectional interdigital transducers via the scanning window technique

An original procedure for optimization of single-phase unidirectional interdigital transducers of surface acoustic waves (SAWs) is described. These transducers are designed for RF filters with low levels of the insertion loss and the triple-transit signal. The optimization algorithm is based on the so-called scanning window technique. Unlike most methods published in the literature, this technique optimizes not continuous (analog) weighting functions of the SAW sources and reflectors but the sequence of base electrode cells; i.e., the technique directly optimizes the transducer topology.     

BNKLT无铅压电陶瓷梯形中频带通滤波器的研制

利用发明的[Bi0.5(Na1-x-yKxLiy)0.5]TiO3(BNKLT)系无铅压电陶瓷,采用全电极径向振动模式制作了插入损耗小于6 dB,阻带损耗大于30 dB,频率特性曲线平滑,并具有良好选择性的中频(IF=460 kHz)多节带通滤波器。与含铅压电陶瓷多节滤波器相比,BNKLT无铅压电陶瓷滤波器的特性有待进一步改进。     

跳频源用低损耗声表面波滤波器

介绍了几种用于跳频源的低损耗声表面波滤波器的制作结果，其插入损耗为４ｄＢ，阻带抑制优于４５ｄＢ。     

SAW Bandpass Filter Design for 1.6-GHz PCM Timing Tank Applications

A 1.6-GHz surface acoustic wave (SAW) timing tank for a self-timed regenerative repeater for an ultrahigh-speed PCM optical fiber transmission system is described. A SAW narrow bandpass filter with 0.74-mu m linewidth interdigital transducers with double electrode geometry and 20-nm aluminum metallization on AT-quartz substrate is realized by conventional optical photolithography. Typical performance obtained is as follows: center frequency f/sub 0/ is 1.5993 GHz; insertion loss is 22 dB; stopband attenuation is above 23 dB with respect to the passbaand; stability is |2Q/sub L//spl dot/Delta f /f/sub 0/| < 0.1, where Q/sub L/ is loaded Q value and Delta f is mistuning due to temperature effects. It is demonstrated that SAW quartz transversal filters can be made into new practical filters which have both high Q value and high stability fn the GHz range and are satisfactory from the standpoints of precise design, fabrication technique, and performance.     

Low-loss low-ripple SAW filters using three bidirectional centrosymmetric transducers

Low-loss, low-ripple and high out-of-band rejection SAW filters have been constructed using a three transducer configuration with symmetric/antisymmetric end transducers. The filter on 128°-cut LiNbO3 has an insertion loss of 5.2 dB, a passband ripple of 0.3 dB (peak to peak) and an out-of-band rejection of 55 dB.     

New fabrication technique for single-phase unidirectional SAW filter (EMUDT) in UHF range

New fabrication techniques for single-phase unidirectional SAW filters (EMUDT) utilising the self-aligned angle-evaporation technique are described. The experimental results show a directivity of 10.0 dB/transducer at 483 MHz.     

1.03 GHz operation of a low-loss SAW filter using 3-phase unidirectional transducers with thin dielectric layered feed electrodes

Successful working of a 3-phase unidirectional transducer (TPUDT) SAW filter at 1.03 GHz, without using any airgap crossovers, is reported in the letter. A thin-film capacitance existing between the feed electrodes of the transducers is used to advantage, as an essential element of the required phaseshifting network. The minimum insertion loss is found to be 2.0 dB. The filter is believed to have wide applications in the present and future communication systems requiring low-loss bandpass filtering.     

Piezoelectric thin film unidirectional SAW transducer and filter

Small passband ripple piezoelectric thin film unidirectional transducers and filters are presented. ZnO thin film deposited on a fused silica was used in the experiment. As the result, the characteristics of no pass-band ripple and minimum insertion loss of 5.2 dB, and also the directionality of 22 to 29 dB per one transducer are obtained.