Collaborative Research: MEMS Tuners for Multiband High-Efficiency Wireless Transmitter Front Ends

该提案提出了用于下一代通信系统的自适应RF前端的设计和实现，该通信系统将需要在多个频带上操作。自适应RF前端将由科罗拉多大学博尔德分校（CU）与格鲁吉亚理工学院（GIT）合作开发，前者在微波高效电路方面具有专长，后者在可调谐RF MEMS方面具有专长。更具体地说，该项目将专注于开发用于所有通信硬件发射机部分的多频段RF功率放大器。目标是演示使用MEMS开关在毫秒级上对调谐阻抗的适应，以用于多频带发射机操作（例如，5.7和24-GHz免许可频带），从而导致更大的总体平均效率和多频带频率覆盖。因此，开关模式PA（E类和F类）将通过多频带MEMS输出电路和可重新配置的MEMS输入电路进行调谐。还将研究使用偏置和驱动控制的多频带高效率功率放大器的线性化，其主要目标是证明这些放大器对于需要线性的调制方案是有利的。这项工作的结果将对全球商用无线系统从2G向更高标准的转变产生直接影响，在更高标准中，RF前端必须支持各种调制方案下的多频段操作。它还可能导致革命性的小型负载牵引系统，取代目前可用的笨重和非常昂贵的负载牵引系统。建议的解决方案符合下一代通信系统的低功耗、小尺寸、低重量和低成本要求。建议的工作为期三年，期间将完成以下工作：o使用MEMSo设计和演示多频段阻抗调谐器使用开关模式拓扑设计和演示多频段高效功率放大器（如E类或F类），在两个输出和输入匹配电路之间进行简单切换使用动态驱动和偏置控制的多频带高效率饱和PA线性化研究放大器和调谐器的集成晶体管与调谐器的集成用于小型化MEMS负载-拟议的研究将得到教育活动的补充，这些活动将把研究结果纳入两所大学的课程和其他相关的外联工作。GIT和CU将为PI提供旅行资金，以访问合作者，并为每学期的本科生和研究生举办研讨会。除了UROP、SMART和SIRF（由各自大学资助的本科研究和少数族裔项目）之外，PI还计划提出REU项目，以便GIT本科生夏季在CU工作，而CU学生则在GIT工作一个学期，目标是两所大学之间的研究生招聘计划。研究人员将遵循NSF的报告要求，并将在同行评审的期刊和会议上公布他们的结果。

0218732PapapolymerouThis proposal addresses design and implementation of adaptive RF front ends for the next generation communication systems that will require operation at several frequency bands. The adaptive RF front ends will be developed by a collaboration between the University of Colorado at Boulder (CU) with expertise in microwave high efficiency circuits, and the Georgia Institute of Technology (GIT) with expertise in tunable RF MEMS.More specifically, this project will focus on the development of a multi-band RF power amplifier used in the transmitter sections of all communication hardware. The goal is to demonstrate adaptation of tuning impedances on the millisecond scale using MEMS switches for multiband transmitter operation (e.g., the 5.7 and 24-GHz unlicensed bands), resulting in a larger overall average efficiency and multi-band frequency coverage. For this reason, switched-mode PAs (classes E and F) will be tuned with a multi-band MEMS output circuit and a reconfigurable MEMS input circuit. Linearization using bias and drive control of multi-band high efficiency PAs will also be studied, with the main goal of proving that these amplifiers are advantageous for modulation schemes that require linearity. Results of this work will have direct impact on worldwide commercial wireless systems moving from 2G to higher standards in which RF front-ends must support multi-band operation under various modulation schemes. It could also potentially lead to revolutionary miniaturized load-pull systems that replace the bulky and very expensive load-pull systems currently available. The proposed solution adheres with the low-power, small-size, low weight and low-cost requirements of next generation communication systems.The proposed effort covers a period of three years during which the following will be accomplished: oDesign and demonstration of a multi-band impedance tuner using MEMSoDesign and demonstration of a multi-band high-efficiency power amplifier using switched-mode topologies (such as classes E or F) with a simple switch between two output and input matching circuitsoStudy of linearization of multiband high efficiency saturated PAs using dynamic drive and bias controloIntegration of the amplifier and tuner oIntegration of transistor with tuners for miniaturized MEMS load-pullThe proposed research will be complemented by educational activities that will integrate the research findings into the curriculum of both universities and other related outreach efforts. GIT and CU will provide travel funds for the PIs to visit the collaborator and give seminars to undergraduate and graduate students each semester. The PIs plan to propose REU projects, in addition to UROP, SMART and SIRFs (undergraduate research and minority programs funded by our respective universities), so that GIT undergraduates work at CU in the summer, while CU students work at GIT for a semester, with the goal of a graduate student recruitment program between the two universities. The investigators will follow NSF's reporting requirements and will also publicize their results in peer reviewed journals and conferences.