声表面波器件叉指换能器的制作技术

声表面波器件的制造关键在于如何制作叉指换能器，特别对于GHz频率以上的器件,亚微米线宽如何控制是声表器件能否制作成功的关键。本文提供了其制作工艺流程及要点。     

叉指换能器模型对声表面波滤波器的影响及其设计考虑

本文论述了叉指换能器(IDT)模型对声表面波滤波器(SAWF)综合设计的影响;指出了现有综合设计方法共同存在的问题;并提出了一种新的设计思想和方法。该方法能将IDT的物理模型直接纳入SAWF综合设计之中,并能消除现有方法不可避免存在的器件实际响应与设计目标响应之间的偏离,提高SAWF的设计精度。     

声表面波叉指换能器的一种新设计方案

采用时域上对脉冲响应直接奇偶分解与校正函数相结合的方法设计叉指换能器.并利用几何刻图数据计算理论频响.理论和实验证明,该方法对频响能进行精细调整.所计算的频响比用常规方法计算的精度高,与实验值吻合更好.可用于各种带宽的滤波器设计.     

声表面波又指换能器的研究与设计

声光可调谐滤波器的设计,关键是它的各个模块,包括光波导、模分离器、声波导和又指换能器的参数设计。设计了叉指换能器各个参数,并对其射频驱动电路和匹配电路给出了设计思路,其中电路控制系统以单片机AT89C52为主控制器,在频率为158MHz频谱仪上得出了频率合成器的测试结果。     

微机械叉指换能器声表面波陀螺

回顾了声表面波(SAW)陀螺发展史，总结了声表面波陀螺设计思想的变迁，重点介绍了一种新型微机械-叉指换能器(MEMS—IDT)声表面波陀螺。它具有适合标准IC工艺生产的简单二维结构，具备体积小、成本低、便于批量生产以及不用真空封装的特点。由于没有普通微机械陀螺的悬浮机构，抗冲击及振动的能力较普通微机械陀螺显著提高。同时，提出了一些迫待解决的问题。     

用叉指换能器制作高频声体波换能器的理论研究

从理论上介绍一种利用叉指换能器制作高频声体波换能器的方法，具有结构和工艺简单，声波模式纯度较高，换能损耗较小和容易消除各种反射波影响的特点。     

声表面波单指无内反射叉指换能器结构及其性能分析

根据我们以前的理论,本文提出了一些常用晶体的各种可能的单指无内反射叉指换能器结构,并分析了影响它们性能的几种因素。其中YZ—LiNbO_3,ST—X石英及X,112°YLiTaO_3上的金或金加铬单指结构存在某些缺点,用途受到较大限制,仅适用于带宽较宽及对中心频率准确度要求不太严格的场合。而上述三种基片上的沟槽填铝结构及Y128°LiNbO_3的铝和铝加铬单指结构是比较好的结构,具有比较广泛的用途。最后给出了我们在ST—X石英上用沟槽填铝单指结构研制的一种高带外抑制窄带滤波器的实验结果。     

Design of Surface Wave Delay Lines with Interdigital Transducers

Design aspects and tradeoffs are presented for nondispersive, analog Rayleigh wave delay lines with interdigital transducers. Design procedures are based on a one-dimensional piezoelectric transducer model whose applicability has been confirmed by experimental data taken on transducers operating at 100 MHz. For transducers with series inductive tuning, optimum aperture and number of interdigital periods are given for several attractive piezoelectrics, such that insertion loss and phase dispersion are minimized while bandwidth is maximized. High-triple transit suppression designs are given for bidirectional transducers, implying some sacrifice in insertion loss. Using directional transducers, low insertion loss and high triple transit suppression are achieved simultaneously at some sacrifice in bandwidth. Finally, two approaches are given for making with presently available piezoelectrics, bandwidths higher than those attainable with a single tuning inductor. The first of these uses a coupled resonator electrical matching network, while the second employs a transducer with graded periodicity.     

Analysis and Design of Dispersive Interdigital Surface-Wave Transducers

A comprehensive circuit model characterization of dispersive interdigital transducers with nonuniform electrode spacing is presented. The model is an extension of a three-port circuit which has been useful for representing periodic transducers. The extended model includes the effects of strong piezoelectric coupling whereby the acoustic waves and electric circuits interact, and it also accounts for reflections of acoustic waves which result from perturbations of the crystal surface by the metal electrodes. The inclusion of the latter effect is shown to be essential for explaining observed levels of triple-transit echos in filters and delay lines. The circuit model is used to derive a transducer design procedure which determines the electrode positions and the anodization function (acoustic aperture taper) required to reproduce a desired waveform. This procedure is applicable to the design of weighted dispersive filters and broad-band nondispersive delay lines. In order to verify the theory a low-loss octave-bandwidth nondispersive delay line was designed using linear FM dispersive transducers on YZ LiNbO/sub 3/. The performance of this device was found to be in good agreement with the circuit model predictions.     

微带抽头式交指型带通滤波器的精确设计

用一个实例介绍一种设计思路,可用于微带抽头式交指型带通滤波器的精确设计,实测数据表明,用这种方法设计出的滤波器具有通带平坦,插损小,且无需调整的特点。     

非线性调频信号产生器

非线性调频脉压线是为雷达系统提供非线性调频信号的特殊器件，该文介绍了这种器件的脉压机理、给出了调频函数表达式和样品实测波形图．探讨了提高旁瓣抑制的途径和研究中存在的问题。     

SAW—IDT波传播分析

分析了声表面波叉指换能器中波的传播问题，从产生ＳＡＷ的静电荷分布出发，结合压电材料的向各异性，推导出了叉指上ＳＡＷ的电势分布及波角谱表达式，引入了波传播损耗因子与修正脉冲响应函数。     

低相噪锁相介质振荡器研究

针对高的相位噪声指标要求,对取样锁相介质振荡器进行了研究.通过相位噪声分析,明晰了采用介质振荡器与取样锁相技术降低相位噪声的机理,并分别对介质振荡器与锁相环路进行了设计.设计中,应用HFSS与ADS对介质振荡器进行了联合仿真,体现了计算机辅助设计的优势.最终研制出17 GHz锁相介质振荡器,测试结果为:输出功率13.1 dBm;杂波抑制>70 dB;谐波抑制>25 dB; 相位噪声为-105 dBc/Hz@1 kHz,-106 dBc/Hz@10 kHz,-111 dBc/Hz@100 kHz,-129 dBc/Hz@1 MHz.     

Reflection and Amplification of Acoustic Surface Waves by Interdigital Transducers with Active Circuit Loading

It has been shown that when the reactance at the electrical port of an interdigital surface-wave transducer is tuned out, near-perfect reflection of acoustic surface waves can be obtained at either acoustic port. An inverted common-collector (ICC) transistor circuit can be used to accomplish this tuning and simultaneously generate a negative resistance that can be used to provide reflection and transmission gain for the surface waves. Some theoretical and experimental results for such a situation in the case of surface waves propagating in the Z direction on Y-cut LiNbO/sub 3/ are presented. In particular, electrically controlled variable (digital) time delay has been demonstrated using this technique.     

数字调制信号识别中的相位去卷叠门限研究

基于瞬时特征提取的数字信号自动识别方法具有重要的应用前景。采用此方法识别信号时,需要提取信号的瞬时幅度、瞬时相位、瞬时频率去计算分类特征参数。但提取信号瞬时相位时会出现相位卷叠现象。本文首先对相位卷叠和相位去卷叠进行了详细的分析,然后提出了一种估计相位去卷叠理论门限范围的方法。而其它相关文献都没对这个门限进行过深入的研究。MATLAB仿真结果表明,采用本文估计出的去卷叠门限范围,可以直接有效地提取信号的非线性瞬时相位。      

巧妙使用Simulink绘制非线性系统的相轨迹

本文通过三个例题介绍了如何用MATLAB中的Sinulink绘制非线形系统的相轨迹。这种方法基本不需编程,只需在Sinulink环境下正确构成仿真结构图即可,既方便又准确。该方法的应用无疑会促进相平面法的进一步发展。     

LC振荡器相位噪声的非线性摄动分析技术

相位噪声是振荡器的重要性能指标,通过对振荡器的非线性微分方程的推导,从而引入新的参数来考虑振幅噪声和相位噪声之间的相关性同时把这些参数和振荡器的工作点联系起来。并且这些公式推导也考虑了LC谐振回路中振幅噪声和相位噪声之间的相关性。在此基础上这里研究了如何在时域状态方程下将噪声看成是对振荡输出信号的小扰动,并建立引入噪声后的随机微分方程,实现LC振荡器的相位噪声分析技术。