An array of small, lightweight acoustic sources was investigated to determine how such an arrangement of sources would acoustically interact with a duct similar to that of a turbofan engine inlet. The sources were cylindrically curved aluminum panels excited in vibration by the application of a sinusoidally varying voltage to a piezoceramic actuator bonded to them. The finite element method was used as a design tool to size the panel based on desired vibration characteristics. A boundary element acoustic analysis was used to predict the acoustic output from various arrangements of sources. The central portion of the research was a series of experiments using an array of twelve sources arranged circumferentially in a duct. Measurements of the performance of each source revealed that the performance of the acoustic sources varied from source to source. This variation was assumed to have been caused by differences in the quality of the bond of each of the piezoceramic actuators to the panels. Directivity measurements were made in the far field. Measurements were also taken of the pressure field established in the duct cross-section. Modal decomposition was applied to the data. It was found that the dominant acoustic modes in the duct are those whose cut-on frequencies were near the frequency of excitation. / Master of Science

No description available.

The monitoring of harmful ambient vapors is of major concern in the industrial environment. To this end, the development of systems which detect and respond in real time to specific vapors is a highly desirable goal. Surface Acoustic Wave (SAW) devices have been used for chemical analysis since 1978. While sensitive to mass changes occurring on their surfaces, they are not selective to the mass they will detect. Their use as chemical sensors requires the development of specificity for a vapor (or class of vapors) using selective chemical reagents suspended in film media that can have their permeability easily changed. This dissertation presents the development of an automated dosimeter for the detection of phosgene using SAW devices. By changing the film media from a very permeable material to a film exhibiting less permeability, the analytical range of the device using the same suspended selective chemical reagent is expanded to concentrations which the very permeable film is incapable of accurately measuring. / Ph. D.

The explosive development of the telecom industry and in particular wireless and mobile communications in recent years has lead to a rapid development of new component and fabrication technologies to continually satisfy the mutually exclusive requirements for better performance and miniaturization on the one hand and low cost on the other. A fundamental element in radio communications is time and frequency control, which in turn is achieved by high performance electro-acoustic components made on piezoelectric single crystalline substrates. The latter, however, reach their practical limits in terms of performance and cost as the frequency of operation reaches the microwave range. Thus, the thin film electro-acoustic technology, which uses thin piezoelectric films instead, has been recently developed to alleviate these deficiencies. This thesis explores and addresses a number of issues related to thin film synthesis on the one hand as well as component design and fabrication on other. Specifically, the growth of highly c-axis textured AlN thin films has been studied and optimized for achieving high device performance. Perhaps, one of the biggest achievements of the work is the development of a unique process for the deposition of AlN films with a mean c-axis tilt, which is of vital importance for the fabrication of resonators operating in contact with liquids, i.e. biochemical sensors. This opens the way for the development of a whole range of sensors and bio-analytical tools. Further, high frequency Lamb wave resonators have been designed, fabricated and evaluated. Performance enhancement of FBAR devices is also addressed, e.g. spurious mode suppression, temperature compensation, etc. It has been demonstrated, that even without temperature compensation, shear mode resonators operating in a liquid still exhibit an excellent performance in terms of Q (200) and coupling (~1.8%) at 1.2 GHz, resulting in a mass resolution better than 2 ng cm-2 in water, which excels that of today’s quartz sensors.

The objective of this dissertation is to develop key components of a CMOS heterodyne millimeter-wave receiver front end. Robust designs are necessary to overcome PVT variations as well as modeling inaccuracies, while with minimum power consumption overhead to facilitate low-power radio for portable applications. Heterodyne receiver topology is adopted because of its robust performances at millimeter-wave frequencies. Device models for both passive and active devices are developed and used in the circuit designs in this dissertation. Two low-noise amplifiers (LNAs) are developed in this dissertation. The first LNA features a proposed temperature-compensation biasing technique, which confines the gain variation within 5 dB for temperature variation from -5 to 85 Celsius degree. The measured gain and NF are 21 and 6.5 dB, respectively, for 49-mW power dissipation. The second LNA reveals a design technique to tolerate a low-accuracy model at millimeter-wave frequencies. Both LNAs provide full coverage of the FCC 60-GHz band (57-64 GHz). For the frequency generation circuits, both the IF QVCO and mm-wave VCO are investigated. The inherent bimodal oscillation of QVCOs is analyzed and, for the first time, a systematic measurement technique is proposed to intentionally control the oscillation mode. This technique is further utilized to extend the tuning range of the QVCO, which possesses dual tuning curves without penalty on phase noise. The measurement results of a 13-GHz QVCO in 90-nm CMOS reveals a 21.4% tuning range for continuously tuning from 11.7 to 14.5 GHz. The measured phase noise is -108 dBc/Hz at 1 MHz offset with a core power consumption of 10.8 mW. A millimeter-wave VCO is designed and fabricated in 65-nm CMOS. The VCO is fully characterized under voltage stress to examine the hot-carrier injection effects affecting the performance of a millimeter-wave VCO. The 41.6-47.4 GHz VCO is further integrated into a millimeter-wave down converter. The power-hungry buffer amplifiers are neglected by proper floor planning. Conversion loss of 1.4 dB is obtained with total power consumption of 72.5 mW. Lastly, a power management system consisting of low-dropout (LDO) regulators is designed and integrated in a 90-nm CMOS millimeter-wave transceiver to provide stable and low-noise supply voltages. Voltage variation issues are alleviated by the LDOs.

Micromachined gyroscopes are attractive replacements to conventional macro-mechanical and optical gyroscopes due to their small size, low power and low cost. The application domain of these devices is quickly expanding from automotive to aerospace and consumer electronics industries. As potential high volume consumer applications for micromachined gyroscopes continue to emerge, design and manufacturing techniques that improve their performance, shock survivability and reliability without driving up the cost and size become important. Today, state-of-the-art micromachined gyroscopes can achieve high performance with low frequency operation (3-30kHz) but at the cost of large form factor, large operating voltages and high vacuum packaging. At the same time, most consumer applications require gyroscopes with fast response time and high shock survivability, which are generally unavailable in low frequency gyroscopes. As a result, innovative designs and fabrication technologies that will offer more practical gyroscopes are desired. In this dissertation, capacitive bulk acoustic wave (BAW) silicon disk gyroscopes are introduced as a new class of micromachined gyroscope to investigate the operation of Coriolis-based vibratory gyroscopes at high frequency and further meet consumer electronics market demands. Capacitive BAW gyroscopes, operating in the frequency range of 1-10MHz are stationary devices with vibration amplitudes less than 20nm, resulting in high device bandwidth and high shock tolerance. They require low operating voltages, which simplifies the interface circuit design and implementation in standard CMOS technologies. They also demonstrate appropriate thermally stable performance in air, which eliminates the need both for vacuum packaging and for temperature control. A revised high aspect ratio poly- and single crystal silicon (HARPSS) process was utilized to implement these devices in thick SOI substrates with very small capacitive gap sizes (~200 nm). The prototype devices show ultra-high quality factors (Q>200,000) and large bandwidth of 15-30Hz. In addition, the design and implementation of BAW disk gyroscopes are optimized for self-matched mode operation. Operating a vibratory gyroscope in matched mode is a straightforward way to improve performance parameters but, is challenging to achieve without applying large voltages. In this work, self-matched mode operation was provided by enhanced design of the perforations of the disk structure. Furthermore, a multi-axis BAW gyroscope, an extension of the z-axis, is developed. This novel approach avoids the issues associated with integrating multiple proof masses, permitting a very small form factor. The multi-axis gyroscopes operate in out-of plane and in-plane modes to measure the rotation rate around the x- and z-axes. These gyroscopes were also optimized to achieve self-matched mode operation in their both modes.

This research discusses the design, fabrication, integration, and characterization of micromachined millimeter-wave components and a signal source for THz multiplier source using the deep reactive ion etching technique. A wide range of advanced micromachined millimeter-wave components are proposed and fully validated with the measurement. These micromachined millimeter-wave passives include: the W-band straight and meander waveguides, W-band three-pole filter, waveguide hybrid and power divider, a novel CPW-to-waveguide transition and filter, and a novel cavity resonator for 60-GHz reconfigurable applications. The proposed THz multiplier source is a broadband 900-GHz silicon micromachined two-anode frequency tripler with the state-of-the-art performance. The research results enable the silicon micromachining technique to build low-loss and low-cost millimeter-wave components and THz signal sources.

With the growing trend of wireless electronics, frequency spectrum is crowded with different applications. High data transfer rate solutions that operate in license-exempt frequency spectrum range are sought. The most promising candidate is the 60 GHz multi-giga bit transfer rate millimeter wave circuit. In order to provide a cost-effective solution, circuits designed in CMOS are implemented in a single SOC. In this work, a modeling technique created in Cadence shows an error of less than 3dB in magnitude and 5 degree in phase for a single transistor. Additionally, less than 3dB error of power performance for the PA is also verified. At the same time, layout strategies required for millimeter wave front-end circuits are investigated. All of these combined techniques help the design converge to one simulation platform for system level simulation. Another aspect enabling the design as a single SOC lies in integration. In order to integrate digital and analog circuits together, necessary peripheral circuits must be designed. An on-chip voltage regulator, which steps down the analog power supply voltage and is compatible with digital circuits, has been designed and has demonstrated an efficiency of 65 percent with the specific area constraint. The overall output voltage ripple generated is about 2 percent. With the necessary power supply voltage, gate voltage bias circuit designs have been illustrated. They provide feasible solutions in terms of area and power consumption. Temperature and power supply sensitivities are minimized in first two designs. Process variation is further compensated in the third design. The third design demonstrates a powerful solution that each aspect of variations is well within 10%. As the DC conditions are achieved on-chip for both the digital and analog circuits, digital and analog circuits must be connected together with a DAC. A high speed DAC is designed with special layout techniques. It is verified that the DAC can operate at a speed higher than 3 Gbps from the pulse-shaping FIR filter measurement result. With all of these integrated elements and modeling techniques, a high data transfer rate CMOS RF SOC operating at 60 GHz is possible.

The object of this thesis research was to develop and characterize a new type of acoustic biosensor - a ZnO-based laterally excited thickness shear mode (TSM) resonator in a solidly mounted configuration. The first specific aim of the research was to develop the theoretical underpinnings of the acoustic wave propagation in ZnO. Theoretical calculations were carried out by solving the piezoelectrically stiffened Christoffel equation to elucidate the acoustic modes that are excited through lateral excitation of a ZnO stack. A finite element model was developed to confirm the calculations and investigate the electric field orientation and density for various electrode configurations. A proof of concept study was also carried out using a Quartz Crystal Microbalance device to investigate the application of thickness shear mode resonators to cancer biomarker detection in complex media. The results helped to provide a firm foundation for the design of new gravimetric sensors with enhanced capabilities. The second specific aim was to design and fabricate arrays of multiple laterally excited TSM devices and fully characterize their electrical properties. The solidly mounted resonator configuration was developed for the ZnO-based devices through theoretical calculations and experimentation. A functional mirror comprised of W and SiO2 was implemented in development of the TSM resonators. The devices were fabricated and tested for values of interest such as Q, and electromechanical coupling (K2) as well as their ability to operate in liquids. The third specific aim was to investigate the optimal surface chemistry scheme for linking the antibody layer to the ZnO device surface. Crosslinking schemes involving organosilane molecules and a phosphonic acid were compared for immobilizing antibodies to the surface of the ZnO. Results indicate that the thiol-terminated organosilane provides high antibody surface coverage and uniformity and is an excellent candidate for planar ZnO functionalization. The fourth and final specific aim was to investigate the sensitivity of the acoustic immunosensors to potential diagnostic biomarkers. Initial tests were performed in buffer spiked with varying concentrations of the purified target antigen to develop a dose-response curve for the detection of mesothelin-rFc. Subsequent tests were carried out in prostate cancer cell line conditioned medium for the detection of PSA. The results of the experiments establish the operation of the devices in complex media, and indicate that the acoustic sensors are sensitive enough for the detection of biomolecular targets at clinically relevant concentrations.

Thesis (Ph.D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Gee-Kung Chang; Committee Co-Chair: Jianjun Yu; Committee Member: John A. Buck; Committee Member: Joy Laskar; Committee Member: Umakishore Ramachandran; Committee Member: Ye Li