CAREER: MEMS Reconfigurable Filters for Multi-Band Low-Power Radios

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This CAREER proposal aims at the development of a single-chip reconfigurable MEMS filter platformfor multi-band, multi-standard radios through fusion of acoustoelectrically amplified nano-mechanicalfilters and 3D tunable components. Reconfigurable filters can greatly enhance the performance andreduce the size of RF front-ends, and as such have received great attention for effective and low-powerprocessing of the frequency spectrum. Despite their great promise, lack of integration and narrowfrequency coverage of current reconfigurable filters continue to hinder their use in practical applications.In addition, current technologies have failed to reduce the size of filters without deteriorating criticalperformance metrics such as loss, power handling and termination impedance. To-date, a versatile andreconfigurable filter array platform does not exist in monolithic form, an important problem that hasremained unsolved despite major advancement in MEMS. This proposal tackles the fundamental issuesrelated to reconfigurable filter arrays and proposes a novel technique that offers frequency, bandwidth andamplitude tunability through integration of narrow-band acoustic filters with tunable lumped filters.These are believed to be the most prominent steps toward the realization of a single-chip multi-band lowpowerradio.Intellectual merits: The proposed work explores a new approach to developing integrated reconfigurablefilters with wide tuning range and reduced loss. This new approach relies on the acoustoelectric effect, aphenomenon caused by interactions between electrons and phonons. Using this effect, which is mosteffective in nano-scale, a new class of nano-mechanical acoustic filters with potentially negative loss (i.e.positive gain) will be developed. This will yield new opportunities for acoustic devices andinstrumentation. In addition, using advanced 3D micromachining techniques microscale tunable lumpedcomponents with unparalleled Qs exceeding 150 and wide tuning range will be developed. The high-Qtunable passives will be utilized to reduce parasitics of acoustic filters and assist in tuning their frequencyresponse. The PI will leverage her prior work on high-Q passives and micro-fabrication techniquestowards this proposed research. Along with the experimental work, the proposed research aims toadvance the scientific community?s understanding of the physical phenomena that govern theperformance of the proposed MEMS arrays and new technologies that overcome these physical limits.Broader Impact: The proposed research enables on-chip reconfigurable high-Q filtering, eliminatingmany of the redundant components in RF transceivers, which results in drastically smaller form factor andreduced power consumption. In a cellular phone, elimination of only one off-chip fixed-frequency filteras well as the associated matching network using the proposed technique reduces the transmit printedcircuit board area by more than 75%, while lowering the bill-of-materials. As such, the proposed researchwill have transformative impact on telecommunication. The reconfigurable MEMS filters developed inthis CAREER program could have far-reaching applications beyond wireless communication rangingfrom medical ultrasonic imaging to non-contact sensing. In addition to the outlined research effort, anintegrated educational program will be established which aims to educate students through directparticipation in the research activities. The outreach efforts of this project are aimed at promotingdiversity among engineers and scientists and specifically increasing the proportion of women inengineering to a healthy level (30%). To reach this goal and to motivate and educate students, the PIwill pursue the following avenues: (1) Educational outreach through School of Education to high schoolteachers to observe the classroom dynamics in the 6th and 7th grades where female students start to loseinterest in engineering as well as summer outreach programs to expose high school students to the field ofMEMS by involving them in the proposed research activities; (2) Involvement of undergraduate studentsfrom underrepresented groups in PI?s research and educational activities; (3) Creating a multi-disciplinaryscientific learning environment for students and training several doctoral students; (4) Introduction of anew graduate course on RF MEMS. Students will gain research experience and discover real worldapplications of RF MEMS through team projects in a laboratory setting; (5) Dissemination of thescientific results of this research.