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

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

0218732 Papapolymerou This 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 MEMS oDesign 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 circuits oStudy of linearization of multiband high efficiency saturated PAs using dynamic drive and bias control oIntegration of the amplifier and tuner oIntegration of transistor with tuners for miniaturized MEMS load-pull The 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.