Intrinsically Switchable Ferroelectric Filter Banks for Frequency Agile and Reconfigurable Radios

下一代无线通信系统应该能够智能地适应环境并重新配置自己，以利用可用的通信信道，同时保持连接、服务质量和较长的电池寿命。这样的系统必须能够快速切换到不同的调制方案和载波频率，以适应所需的带宽，最大限度地减少功耗和干扰。无线电中使用的集成电路的性能和功能在很大程度上是由于器件规模的扩大而稳步提高的。相比之下，频率选择元件(如滤光器)和辐射元件等无源器件并不遵循摩尔定律对有源器件预测的进步。目前，在通信系统的规模、复杂性和成本中，很大一部分是由滤波器、开关和天线构成的。拟议项目的目标是为下一代通信系统开发高性能和紧凑的压控声谐振器和滤波器，这些谐振器和滤波器工作在射频和微波频率。发展对电致伸缩薄膜铁电材料中声波产生的理解将影响其他领域，如声光和传感器。这项建议的一个重要组成部分是本科生和研究生的研究型教育。由于其多学科性质，该研究对学生具有特别的价值，涉及薄膜材料沉积和表征、射频滤波器设计、微电子机械器件制造、声谐振器设计、制造和表征。该项目的目标是利用薄膜钛酸锶(BST)的电致伸缩特性开发压控体声波谐振器(FBAR)滤波器组。铁电BST是一种多功能材料，具有许多理想的特性，可用于设计本征开关谐振器和滤波器。施加直流电压可以改变铁电材料的极化，从而改变电致伸缩的强度。这种效应是独一无二的，并提供了一种通过施加直流偏置来控制声波产生的方法。设计新型铁电BST FBAR滤波器组的研究方法将结合薄膜材料生长和基于薄膜铁电材料所特有的特性的滤波器设计。结合电路级设计，将进行结构多物理模拟，以优化器件结构以获得最佳性能。可开关射频谐振器的设计将利用优化设计的薄膜BST FBAR的高品质因数、高有效机电耦合系数和偏压相关的压电响应。这种设计方法将导致开发高性能的可切换谐振器、滤波器，并最终在无线电频率上开发滤波器组。

The next generation of wireless communication systems should be able to intelligently adapt to the environment and reconfigure themselves to exploit available communication channels while maintaining connectivity, quality of service, and a long battery life. Such systems must be able to rapidly switch to different modulation schemes and carrier frequencies to accommodate the required bandwidth, minimize power consumption and interference. The performance and functionality of integrated circuits used in radios has steadily improved mostly as a result of device scaling. In contrast, passive devices such as frequency selective components (like filters) and radiating elements do not follow advances predicted by Moore's law for active devices. Currently, filters, switches and antennas contribute to a large portion of the communications systems size, complexity and cost. The goal of the proposed project is to develop high-performance and compact voltage controlled acoustic resonators and filters operating at radio frequency (RF) and microwave frequencies for the next generation of communications systems. Developing an understanding of acoustic wave generation in electrostrictive thin film ferroelectrics will impact other areas such as acousto-optics and sensors. An important component of this proposal is the research-based education of both undergraduate and graduate students. The research is of particular value for students due to its multidisciplinary nature, involving thin film materials deposition and characterization, RF filter design, microelectromechanical device fabrication, acoustic resonator design, fabrication and characterization. The objective of the proposed project is to develop voltage-controlled bulk acoustic wave resonator (FBAR) filter banks by employing the electrostrictive property of thin-film barium strontium titanate (BST). Ferroelectric BST is a multifunctional material exhibiting many desirable characteristics that can be exploited for the design of intrinsically switched resonators and filters. The application of a DC voltage can be used to change the polarization in ferroelectric material, thereby changing the strength of electrostriction. This effect is unique, and offers a means of controlling the generation of acoustic waves through application of a DC bias. The research approach for the design of novel ferroelectric BST FBAR filter banks will combine thin-film material growth with filter design based on specific properties that are unique to thin-film ferroelectrics. In conjunction with circuit-level design, structural multi-physics simulations will be conducted to optimize the device structure for best performance. The design for switchable RF resonators will utilize the high quality factor, high effective electromechanical coupling coefficient and bias-voltage-dependent piezoelectric response of optimally designed thin-film BST FBARs. The design approach will lead to the development of high-performance switchable resonators, filters, and ultimately filter banks at radio frequencies.