Magnetic Transduction for RF Micromechanical Filters

Forouzanfar, Sepehr

Magnetic Transduction for RF Micromechanical Filters

dc.contributor.author	Forouzanfar, Sepehr
dc.date.accessioned	2012-02-27T15:10:56Z
dc.date.available	2012-02-27T15:10:56Z
dc.date.issued	2012-02-27T15:10:56Z
dc.date.submitted	2012-02-21
dc.description.abstract	The use of electrostatic transduction has enabled high-Q miniaturized mechanical resonators made of non-piezoelectric material that vibrate at high and ultra high frequencies. However, this transduction technique suffers from large values of motional resistance associated with the technique, limiting its use for interfacing to standard 50 RF circuits. Piezoelectric transduction has advantages over the electrostatic method because of its comparable to 50 motional resistance. However, the technique requires use of thin film piezoelectric materials with the demonstrated Qs that are much lower than their corresponding non-piezoelectric resonators. This research proposes use of electrodynamic transduction, reports analytic and experimental studies on electrodynamic transduction for RF application, highlights the method’s advantages, and lists the contributions. The use of Lorentz-force transduction for RF micromechanical filters proposed in this work is pursued by experimentally evaluating the transduction technique implemented for microfabricated designs. By fabricating single and coupled microresonators in a few different fabrication technologies, including CMOS35, the performance of the Lorentz-force driven microresonators is studied. Using a laser vibrometer, the actual performance, including the displacement and velocity of the moving points of the microstructures’ surfaces, are measured. The mode shapes and resonance specifications of the microstructures in air and vacuum derived by laser vibrometer provide data for characterizing the employed Lorentz-force transduction technique. Furthermore, the results from the electrical measurements are compared to the micromechanical resonators’ frequency response obtained from the mechanical measurements by laser vibrometer. The significantly low values of motional resistance computed for the differently fabricated designs demonstrate the advantage of Lorentz-force transduction for RF filter applications. Should a device similar in size be driven electrostatically, the motional resistance would be multiple orders of magnitude higher. This research reports the experimental results obtained by examining a Lorentz- force transduction application for developing RF micromechanical filters. The results demonstrate the Lorentz-force transduction’s advantages over other transduction methods used for RF μ-mechanical filters. Compared to electrostatic transduction, the Lorentz-force method provides greater electromechanical coupling, multiple orders of magnitude lower motional resistance, the independence of the filter center frequency from the bias voltage, higher power handling, and no requirement for bias lines, which decreases the work in microfabrication. Unlike piezoelectric transduction, the electrodynamic technique requires no piezoelectric material. Use of non-piezoelectric materials provides more flexibility for resonator material in the IC-compatible fabrications. Power handling in electrodynamic transduction has fewer limitations than other transduction techniques because the higher power needed in electrostatic or piezoelectric methods requires a higher voltage, which is limited by the breakdown voltage. The higher power in Lorentz-force-based transduction demands a larger current. The larger current produces heat that is removable by applying an appropriate cooling technique.	en
dc.identifier.uri	http://hdl.handle.net/10012/6575
dc.language.iso	en	en
dc.pending	false	en
dc.publisher	University of Waterloo	en
dc.subject	Lorentz force	en
dc.subject	transduction	en
dc.subject	micromechanical	en
dc.subject	resonator	en
dc.subject	filter	en
dc.subject	MEMS	en
dc.subject	electrodynamic	en
dc.subject	RF	en
dc.subject.program	Electrical and Computer Engineering	en
dc.title	Magnetic Transduction for RF Micromechanical Filters	en
dc.type	Doctoral Thesis	en
uws-etd.degree	Doctor of Philosophy	en
uws-etd.degree.department	Electrical and Computer Engineering	en
uws.peerReviewStatus	Unreviewed	en
uws.scholarLevel	Graduate	en
uws.typeOfResource	Moving Image	en
uws.typeOfResource	Text	en