Microelectromechanical Systems for Wireless Radio Front-ends and Integrated Frequency References.

Microelectromechanical systems (MEMS) have great potential in realizing chip-scale integrated devices for energy-efficient analog spectrum processing. This thesis presents the development of a new class of MEMS resonators and filters integrated with CMOS readout circuits for RF front-ends and integrated timing applications. Circuit-level innovations coupled with new device designs allowed for realizing integrated systems with improved performance compared to standalone devices reported in the literature. The thesis is comprised of two major parts. The first part of the thesis is focused on developing integrated MEMS timing devices. Fused silica is explored as a new structural material for fabricating high-Q vibrating micromechanical resonators. A piezoelectric-on-silica MEMS resonator is demonstrated with a high Q of more than 20,000 and good electromechanical coupling. A low phase noise CMOS reference oscillator is implemented using the MEMS resonator as a mechanical frequency reference. Temperature-stable operation of the MEMS oscillator is realized by ovenizing the platform using an integrated heater. In an alternative scheme, the intrinsic temperature sensitivity of MEMS resonators is utilized for temperature sensing, and active compensation for MEMS oscillators is realized by oven-control using a phase-locked loop (PLL). CMOS circuits are implemented for realizing the PLL-based low-power oven-control system. The active compensation technique realizes a MEMS oscillator with an overall frequency drift within +/- 4 ppm across -40 to 70 °C, without the need for calibration. The CMOS PLL circuits for oven-control is demonstrated with near-zero phase noise invasion on the MEMS oscillators. The properties of PLL-based compensation for realizing ultra-stable MEMS frequency references are studied. In the second part of the thesis, RF MEMS devices, including tunable capacitors, high-Q inductors, and ohmic switches, are fabricated using a surface micromachined integrated passive device (IPD) process. Using this process, an integrated ultra-wideband (UWB) filter has been demonstrated, showing low loss and a small form factor. To further address the issue of narrow in-band interferences in UWB communication, a tunable MEMS bandstop filter is integrated with the bandpass filter with more than an octave frequency tuning range. The bandstop filter can be optionally switched off by employing MEMS ohmic switches co-integrated on the same chip.PhDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/109069/1/zzwu_1.pd

A SYSTEM-ON-CHIP 1.5 GHz PHASE LOCKED LOOP REALIZED USING 40 nm CMOS TECHNOLOGY

This work presents the design and realization of a fully-integrated 1.5 GHz sigma-delta fractional-N ring-based PLL for system-on-chip (SoC) applications. Some design optimizations were conducted to improve the performance of each functional block such as phase frequency detector (PFD), voltage-controlled oscillator (VCO), filter and charge pump (CP) and so as for the whole system. In particular, a time delay circuit is designed for overcoming the blind zone in the PFD; an operational amplifierfeedback structure was used to eliminate the current mismatch in the CP, a 3rd LPF is used for suppressing noises and a current overdrive structure is used in VCO design. The design was realized with a commercial 40 nm CMOS process. The core die sized about 0.041 mm2. Measurement results indicated that the circuit functions well for the locked range between 500 MHz to 1.5 GHz

Lithium niobate RF-MEMS oscillators for IoT, 5G and beyond

This dissertation focuses on the design and implementation of lithium niobate (LiNbO3) radiofrequency microelectromechanical (RF-MEMS) oscillators for internet-of-things (IoT), 5G and beyond. The dissertation focuses on solving two main problems found nowadays in most of the published works: the narrow tuning range and the low operating frequency (sub 3 GHz) acoustic oscillators currently deliver. The work introduced here enables wideband voltage-controlled MEMS oscillators (VCMOs) needed for emerging applications in IoT. Moreover, it enables multi-GHz (above 8 GHz) RF-MEMS oscillators through harnessing over mode resonances for 5G and beyond. LiNbO3 resonators characterized by high-quality factor (Q), high electromechanical coupling (kt2), and high figure-of-merit (FoMRES= Q kt2) are crucial for building the envisioned high-performance oscillators. Those oscillators can be enabled with lower power consumption, wider tuning ranges, and a higher frequency of oscillation when compared to other state-of-the-art (SoA) RF-MEMS oscillators. Tackling the tuning range issue, the first VCMO based on the heterogeneous integration of a high Q LiNbO3 RF-MEMS resonator and complementary metal-oxide semiconductor (CMOS) is demonstrated in this dissertation. A LiNbO3 resonator array with a series resonance of 171.1 MHz, a Q of 410, and a kt2 of 12.7% is adopted, while the TSMC 65 nm RF LP CMOS technology is used to implement the active circuitry with an active area of 220×70 µm2. Frequency tuning of the VCMO is achieved by programming a binary-weighted digital capacitor bank and a varactor that are both connected in series to the resonator. The measured best phase noise performances of the VCMO are -72 and -153 dBc/Hz at 1 kHz and 10 MHz offsets from 178.23 and 175.83 MHz carriers, respectively. The VCMO consumes a direct current (DC) of 60 µA from a 1.2 V supply while realizing a tuning range of 2.4 MHz (~ 1.4% tuning range). Such VCMOs can be applied to enable ultralow-power, low phase noise, and wideband RF synthesis for emerging applications in IoT. Moreover, the first VCMO based on LiNbO3 lateral overtone bulk acoustic resonator (LOBAR) is demonstrated in this dissertation. The LOBAR excites over 30 resonant modes in the range of 100 to 800 MHz with a frequency spacing of 20 MHz. The VCMO consists of a LOBAR in a closed-loop with two amplification stages and a varactor-embedded tunable LC tank. By the bias voltage applied to the varactor, the tank can be tuned to change the closed-loop gain and phase responses of the oscillator so that Barkhausen’s conditions are satisfied for the targeted resonant mode. The tank is designed to allow the proposed VCMO to lock to any of the ten overtones ranging from 300 to 500 MHz. These ten tones are characterized by average Qs of 2100, kt2 of 1.5%, FoMRES of 31.5 enabling low phase noise, and low-power oscillators crucial for IoT. Owing to the high Qs of the LiNbO3 LOBAR, the measured VCMO shows a close-in phase noise of -100 dBc/Hz at 1 kHz offset from a 300 MHz carrier and a noise floor of -153 dBc/Hz while consuming 9 mW. With further optimization, this VCMO can lead to direct RF synthesis for ultra-low-power transceivers in multi-mode IoT nodes. Tackling the multi-GHz operation problem, the first Ku-band RF-MEMS oscillator utilizing a third antisymmetric overtone (A3) in a LiNbO3 resonator is presented in the dissertation. Quarter-wave resonators are used to satisfy Barkhausen’s oscillation conditions for the 3rd overtone while suppressing the fundamental and higher-order resonances. The oscillator achieves measured phase noise of -70 and -111 dBc/Hz at 1 kHz and 100 kHz offsets from a 12.9 GHz carrier while consuming 20 mW of dc power. The oscillator achieves a FoMOSC of 200 dB at 100 kHz offset. The achieved oscillation frequency is the highest reported to date for a MEMS oscillator. In addition, this dissertation introduces the first X-band RF-MEMS oscillator built using CMOS technology. The oscillator consists of an acoustic resonator in a closed loop with cascaded RF tuned amplifiers (TAs) built on TSMC RF GP 65 nm CMOS. The TAs bandpass response, set by on-chip inductors, satisfies Barkhausen's oscillation conditions for A3 only. Two circuit variations are implemented. The first is an 8.6 GHz standalone oscillator with a source-follower buffer for direct 50 Ω-based measurements. The second is an oscillator-divider chain using an on-chip 3-stage divide-by-2 frequency divider for a ~1.1 GHz output. The standalone oscillator achieves measured phase noise of -56, -113, and -135 dBc/Hz at 1 kHz, 100 kHz, and 1 MHz offsets from an 8.6 GHz output while consuming 10.2 mW of dc power. The oscillator also attains a FoMOSC of 201.6 dB at 100 kHz offset, surpassing the SoA electromagnetic (EM) and RF-MEMS based oscillators. The oscillator-divider chain produces a phase noise of -69.4 and -147 dBc/Hz at 1 kHz and 1 MHz offsets from a 1075 MHz output while consuming 12 mW of dc power. Its phase noise performance also surpasses the SoA L-band phase-locked loops (PLLs). The demonstrated performance shows the strong potential of microwave acoustic oscillators for 5G frequency synthesis and beyond. This work will enable low-power 5G transceivers featuring high speed, high sensitivity, and high selectivity in small form factors

Optical Gas Sensing: Media, Mechanisms and Applications

Optical gas sensing is one of the fastest developing research areas in laser spectroscopy. Continuous development of new coherent light sources operating especially in the Mid-IR spectral band (QCL—Quantum Cascade Lasers, ICL—Interband Cascade Lasers, OPO—Optical Parametric Oscillator, DFG—Difference Frequency Generation, optical frequency combs, etc.) stimulates new, sophisticated methods and technological solutions in this area. The development of clever techniques in gas detection based on new mechanisms of sensing (photoacoustic, photothermal, dispersion, etc.) supported by advanced applied electronics and huge progress in signal processing allows us to introduce more sensitive, broader-band and miniaturized optical sensors. Additionally, the substantial development of fast and sensitive photodetectors in MIR and FIR is of great support to progress in gas sensing. Recent material and technological progress in the development of hollow-core optical fibers allowing low-loss transmission of light in both Near- and Mid-IR has opened a new route for obtaining the low-volume, long optical paths that are so strongly required in laser-based gas sensors, leading to the development of a novel branch of laser-based gas detectors. This Special Issue summarizes the most recent progress in the development of optical sensors utilizing novel materials and laser-based gas sensing techniques

Microelectromechanical Systems and Devices

The advances of microelectromechanical systems (MEMS) and devices have been instrumental in the demonstration of new devices and applications, and even in the creation of new fields of research and development: bioMEMS, actuators, microfluidic devices, RF and optical MEMS. Experience indicates a need for MEMS book covering these materials as well as the most important process steps in bulk micro-machining and modeling. We are very pleased to present this book that contains 18 chapters, written by the experts in the field of MEMS. These chapters are groups into four broad sections of BioMEMS Devices, MEMS characterization and micromachining, RF and Optical MEMS, and MEMS based Actuators. The book starts with the emerging field of bioMEMS, including MEMS coil for retinal prostheses, DNA extraction by micro/bio-fluidics devices and acoustic biosensors. MEMS characterization, micromachining, macromodels, RF and Optical MEMS switches are discussed in next sections. The book concludes with the emphasis on MEMS based actuators

EUROSENSORS XVII : book of abstracts

Fundação Calouste Gulbenkien (FCG).Fundação para a Ciência e a Tecnologia (FCT)

Technology 2001: The Second National Technology Transfer Conference and Exposition, volume 2

Proceedings of the workshop are presented. The mission of the conference was to transfer advanced technologies developed by the Federal government, its contractors, and other high-tech organizations to U.S. industries for their use in developing new or improved products and processes. Volume two presents papers on the following topics: materials science, robotics, test and measurement, advanced manufacturing, artificial intelligence, biotechnology, electronics, and software engineering

Biosensors for Diagnosis and Monitoring

Biosensor technologies have received a great amount of interest in recent decades, and this has especially been the case in recent years due to the health alert caused by the COVID-19 pandemic. The sensor platform market has grown in recent decades, and the COVID-19 outbreak has led to an increase in the demand for home diagnostics and point-of-care systems. With the evolution of biosensor technology towards portable platforms with a lower cost on-site analysis and a rapid selective and sensitive response, a larger market has opened up for this technology. The evolution of biosensor systems has the opportunity to change classic analysis towards real-time and in situ detection systems, with platforms such as point-of-care and wearables as well as implantable sensors to decentralize chemical and biological analysis, thus reducing industrial and medical costs. This book is dedicated to all the research related to biosensor technologies. Reviews, perspective articles, and research articles in different biosensing areas such as wearable sensors, point-of-care platforms, and pathogen detection for biomedical applications as well as environmental monitoring will introduce the reader to these relevant topics. This book is aimed at scientists and professionals working in the field of biosensors and also provides essential knowledge for students who want to enter the field