声表面波滤波器的环境电磁干扰特性研究

【作者】 方小燕；

【导师】 胡皓全；

【作者基本信息】 电子科技大学 ， 无线电物理， 2005， 硕士

【摘要】 声表面波(SAW)器件是一种新型的利用声波特性的模拟信号处理器件。声表面波技术[1]自诞生三十多年来,因其用途广泛而得到迅速的发展,同时其性能也在不断地提高。由于SAW 器件性能优良、重量轻、体积小、一致性好,广泛地应用于现代微波信、雷达等系统中。随着SAW 滤波器、放大器在电子对抗、雷达和通信系统中的大量使用,以及SAW 高频器件的飞速发展,电磁环境日趋复杂,电磁干扰问题日益突出,电磁干扰和兼容技术在器件设计、研制和生产过程中是必须考虑的。本课题将针对SAW 器件及相关电路,从电磁兼容角度分析研究SAW 器件的电磁干扰机理和抗干扰特性。本文分别建立了外部电磁场和孔缝泄漏场对传输线干扰耦合的等效模型,利用传输线理论及软件仿真对该模型进行了详细分析和理论计算,从而计算出连接线上感应的终端电压随外部电磁场的变化特性,再将所求得的感应电压作为即将进入SAW 器件的肇事干扰源,并结合SAW 器件的外电路特性分析,最后给出了SAW 器件输出端口的干扰电压随外部电磁场及孔缝泄漏场变化的结果。本文还分析了SAW 滤波器上面引线间的串扰问题,简化为平行双导线间串扰的耦合模型进行分析。主要从分析平行导线间电容性干扰和电感性干扰入手,最后将两干扰结合求出了总串扰随干扰线信号源的变化特点。另外,本文还初步分析了SAW 滤波器三次渡越回波(TTE)的产生机理及常用的解决办法;SAW滤波器的衍射及补偿办法;最后介绍了用雷米兹(Remez)法设计SAW 滤波器的指条加权系数,这对改善滤波器的带外抑制具有重要的意义。本文的工作就是顺应军用和民用技术需求而进行的,研究的结果对在设计SAW 器件的初期具有重要的指导意义以及提高其在复杂电磁环境中使用的稳定性和可靠性有很大的实用价值。更多还原

【Abstract】 Surface acoustic wave(SAW) device is an advanced analog signal processing device by means of acoustic wave character. Since SAW technologies is applied thirty years ago, SAW devices accelerate growth because of their broad use and in the meantime their performance are raised constantly. Because its high performance, light weight and good consistency, it is widely used in modern microwave communication and radar system and so on. With SAW filters and amplifiers used in electronic warfare, radar and communication system, electromagnetic interference (EMI) of SAW devices is evident day and day. So SAW device technologies of the EMI and electromagnetic compatibility in its process of design, fabrication and production must be considered. Aiming at SAW devices and theirs correlative circuits, the interference mechanism and interference immunity character are analyzed in this paper. This paper has built up equivalent models of the interference of external electromagnetic fields and coupling fields through an aperture to wires. Terminal induced voltage changes due to signal frequency are analyzed and calculated by transmission line theory and CAD simulation, which will enter SAW devices. Combining the external circuits character of SAWD and Y matrix, disturbed voltage of the SAWD export is derived. This paper also analyzes crosstalk coupling of SAWF down-leads by the coupling model between two parallel transmission lines. The total crosstalk coupling response to signal frequency is derived from analyzing the capacitance-coupling and inductance-coupling between parallel lines. Besides, this paper also analyze simply the reason bringing triple-transit-echo(TTE) and measure of reducing it. Finally we also use Remez exchange to design SAWF, which may improve the performance of SAWF. This paper meets the requirements of military and civil use. If this research work can be applied in future, it is a practical value to improve the stabilization and credibility of SAW device in complex electromagnetic circumstance.更多还原