The ubiquity of high quality video and proliferation of mobile devices has contributed to an unprecedented rise in video consumption. HTTP, in conjunction with adaptive streaming, has become the de facto mechanism for delivering the vast majority of video as it readily caters to heterogeneous networks and devices. This dissertation...
In this dissertation, we explored multiple coding techniques to reduce energy consumption, improve performance, and secure wireless sensor networks specifically and ad-hoc networks in general. With the introduction of Internet of Things (IoT) and 5G technologies, wireless sensor networks are quickly emerging as an important and key technology in the...
This dissertation focuses on the application of diatom frustules, the biosilica shell of an algae possessing physical and photonic properties capable of enhancing optical signals, for the enhancement of optical sensing. In this work, we incorporate diatom frustules into biosensors for signal enhancement and improved target molecule detection. The potential...
Metal-insulator-metal (MIM) and dual-insulator MIM (MIIM) devices are used in rectennas, hot-electron transistors, single electron transistors, resistive random access memory (RRAM), and capacitors. The performance of these devices relies heavily on the energy barrier height at each metal-insulator interface. Thus, determination of the in-situ electron energy barrier at each interface...
Successive-approximation-register (SAR) analog-to-digital converters are popular for medium accuracy, medium speed and low power applications, such as in biomedical applications. They have low latency and simple architecture compared with ΔΣ ADCs. This is because of SAR ADCs’ binary searching scheme. Furthermore, SAR ADCs can apply oversampling and noise shaping schemes...
Ring amplifiers (ringamps) have shown excellent power efficiency in the latest state-of-the-art analog to digital converters (ADCs). This thesis describes circuit techniques to ensure robust operation of ringamps using standard analog techniques and proportional-integral-derivative(PID) controller analogy. Large-signal and small-signal analysis of a ringamp are performed using simple RC settling and...
Harvesting energy from ambient sources can provide power autonomy to energy efficient electronics and sensors. The last decade has seen a multitude of ways to scavenge energy from various sources like solar, thermal, electromagnetic, electrostatic, piezo-electric and many more. Thermal energy from human body heat is ubiquitous and can be...
Over the last decades, CMOS-integrated sensors have made impressive progress in performance, form-factor, and energy-efficiency for various applications such as imaging, physical/chemical sensing, bio/health monitoring. In the era of the artificial intelligence (AI) and the internet-of-things (IoT), such CMOS-integrated sensors are essential for massive and comprehensive data acquisition, where sensing...
This research focuses on receiver architectures which enable better spectral eciency
by handling blockers in the same spectral range as the signal. The presence of
such blockers, without the use of blocker cancelling/ltering techniques leads to gain
compression and hence, consequent performance degradation of receivers leading to
reduced spectrum...
Traditional approaches to streaming H.264 video over a network typically rely on a single method of transport (i.e., reliable or unreliable) and/or use static values for parameters that can have a significant negative impact on the perceptual quality of the received video. This dissertation presents a dynamic method for wireless...
Modern communication systems often have the ability to transmit signals on multiple communication mediums (e.g., RF, visible light) or interfaces (e.g., MAC layer protocols) at the same time. While each channel has different characteristics, a centralized controller with channel condition information will be able to schedule the resource allocated to...
Structural health monitoring (SHM) systems perform automated non-destructive damage detection and characterization for a variety of large structures including civil structures such as bridges and aerospace structures such as aircrafts and space vehicles. The goals of SHM include preventing catastrophic structural failures, increasing reliability, reducing maintenance costs, and increasing the...
There are nearly two million limb amputees living in the United States of America. Loss of limbs results in profound changes in one's life. However, the underlying neural circuitry and much of the ability to sense and control movements of their missing limb is retained even after limb loss. This...
Load flow studies are one of the most essential engineering applications for grid operators because they provide a clear picture of the operating conditions of the power system. Traditionally, the load flow problem is assumed to be deterministic; that is, the system variables contain no randomness. Unfortunately, this assumption is...
Conventional Delta-Sigma analog-to-digital converters (ADCs) utilize operational transconductance amplifiers (OTAs) in their loop filter implementation followed by multi-bit voltage domain quantizers. As CMOS integrated circuit technology scales to smaller geometries, the minimum transistor length and the intrinsic gain of the transistors decrease. Moreover, with process scaling the voltage headroom decreases...
In recent years, SAR ADCs have been shown to acheive faster conversion times and improved power efficiencies due to their simple building blocks that are digital in nature and scale favorably with technology. High resolution ADCs with stringent noise requirement has led to the adoption of hybrid ADC architectures such...
As the power system grows larger and more complex, real-time monitoring and control become very significant in order to achieve reliable operation of the power system. Before any security assessment can be made or control actions are taken, the reliable estimate of the existing state of the system must be...
With the rapid growth of worldwide internet traffic in data centers and clouds, silicon photonics has been utilized to provide enormous data bandwidth and outstanding energy efficiency over electronics. Computing servers and storage servers that are connected by communication links are relying more on optical rather than electrical means mainly...
Efficient time-series analysis can impact multiple application domains such as motif discovery in gene analysis or music data, extracting spectro-temporal patterns in acoustic scene analysis, or annotating and classifying electrical bio-signals (such as ECG, EEG, and EMG) for medical applications.
Time-series analysis involves a variety of tasks.
To predict future...
Low-power millimeter-wave (mm-wave) transceivers are of interest for achieving energy-efficient high data rate short-reach wireless and guided-wave links.
Spatial modulation or space-shift keying (SSK) can provide energy efficiency improvements by using antenna-switching or transmission direction switching for data modulation. Such links are particularly attractive at millimeter-wave frequencies due to small...
Millimeter-wave (mm-wave) technology promises high speed, high system capacity and low latency interconnects with reduced cost. Applications like high data-rate wireless links, next generation automotive sensors and security body scanners highly depend on mm-wave technology innovations. As operating frequency moves to higher mm-wave bands, shrinking antenna dimensions enable co-integration of...
The Pacific Northwest is part of the "Ring of Fire," which is well-known for heavy seismic activity. Numerous active faults in the area have encouraged electric grid managers in the region to more deeply contemplate and proactively intervene to support grid resilience. This research introduces Monte Carlo (MC) based power...
Due to the continued evolution of 5G standards, the need for higher rates of data, lower latency network access, and implementations that are more energy efficient have become clear. To enable wireless communications at rates over tens of Gbps, the wide bandwidth of mmWave spectrum can be exploited. Beamforming (or...
Portable, high power efficiency communication devices is a growing market in the semiconductor industry. Analog-to-digital converters (ADC) are key interface that are used to digitize the sensed information. Recently, digital techniques have been proposed to improve analog building block power efficiency in sub-micron technologies. This research focuses on mixed signal...
Noise-shaping multibit quantizers in a ΔΣ modulator offer extra orders of noise shaping without increasing the loop-filter order and without compromising the stability of the modulator. This dissertation presents two new architectures for improving the overall performance of continuous-time ΔΣ modulators using noise-shaped quantizers.
The first modulator architecture is motivated...
Filters and data converters are key analog-and-mixed-signal (AMS) building blocks in communication systems, such as software-defined radios and internet-of-things. In this dissertation, novel switched-capacitor filter and analog-to-digital converter (ADC) circuit configurations have been explored which are power efficient and are digital scaling friendly.
First, a novel switched-capacitor low-pass filter architecture...
For mmWave Integrated Circuit (IC) design, co-integration of passives can reduce size and power consumption, increase reliability, and reduce overall cost. However, skin and proximity effects in the metallization are aggravated at mmWave frequencies, resulting in increased attenuation and degradation of overall performance. Furthermore, tight integration of passive components (to...
Renewable electrical energy sources are relatively easy to integrate at moderate penetrations, utilizing a combination of technical and market methods to increase grid flexibility. However, integrating high renewable portfolios is more challenging, and the optimal combination of resources will vary depending on the features of specific geographic areas. This study...
The scarcity of wireless spectrum resources and the overwhelming demand for wireless broadband resources have prompted industry, government agencies and academia within the wireless communities to develop and come up with effective solutions that can make additional spectrum available for broadband data. As part of these ongoing efforts, cognitive radio...
The dissertation focuses on the engineering of light-matter interaction using plasmonic nanoparticles and metamaterials to achieve enhanced luminescence and based on which to improve the performance of biosensing and light-emitting technologies. We designed and fabricated a spectrum of nanostructures to exhibit particular dispersion relations capable of controlling the spontaneous emission...
With the increasing penetration of renewable energy integration and potential threats from natural disasters, modern electric power system have been significantly exposed to both small- and large-scale disturbances. Traditional performance metrics including indices of reliability, stability, and security are no longer adequate to describe a power network. Infrastructure properties like...
Besides enabling an enhanced mobile broadband access, fifth-generation (5G) wireless mobile networks are envisioned to support the connectivity of massive, heterogeneous Internet of Things (IoT) devices. Connecting these devices through 5G systems and providing them with their needed data rates require huge amounts of spectrum and power resources, thus calling...
Modern sensor network applications are often implemented wirelessly in order to lessen installation costs and reduce deployment times. Unfortunately, these wireless sensor network (WSN) nodes must often rely on batteries or energy harvesting techniques in order to sustain their operation and supply the power needed to maintain communication within the...
The prevalence of Internet-of-Things (IoT) applications leads to an increasing focus on the design and optimization of sensor nodes. Battery lifetime and associated costs of battery replacement often limits the long term operation and viability of sensor nodes. RF wireless energy harvesting on the other hand can be appealing since...
Analog-to-digital converters are essential components to the portable devices that we are using today. Wireless sensors, body implanted devices, communication devices and so forth require low power ADCs. Therefore achieving higher resolution and bandwidth with lower power consumption is targeted in ADCs design. In this work power efficient ADCs for...
Demands of today's integrated society dependent on communication systems have driven the creation of ever more efficient analog-to-digital converters. For the same reasons, digital circuitry has rapidly expanded to serve all the different systems and needs of consumers. The trend of technology development has been to make these digital circuits...
This dissertation focuses on extending the application scope of surface enhanced infrared absorption spectroscopy to gas sensing. The method we propose is incorporating plasmonic nanostructures with nano-composite material, metalorganic framework, which can selectively preconcentrate certain gas molecules into the nanopores. The preconcentrating property is first demonstrated by applying metal-organic framework...
Scalable array transceivers with wide frequency tuning range are attractive for next-generationradios. Key challenges for such radios include generation of LO signals with widefrequency tuning range, scalable synchronization between multiple array unit cells andtolerance to in-band and out-of-band interferers. This thesis presents approaches toaddress these challenges in commercial CMOS technologies.The...
When the term renewable energy is mentioned in a conversation, wind, solar, and hydro energy typically come to mind. However, there is one major resource that has remained mostly untapped: wave energy. Wind and solar power technologies are well established around the world but they cannot generate electricity all the...
Wave energy converters (WECs) are a broad class of emerging technology that converts hydrokinetic energy into some other useful form, such as electricity. The last stage in this transformation, the power take-off (PTO) subsystem, is often not experimentally evaluated until half-way through the recommended development process. This delay in evaluation...
Most of today’s Internet of Things (IoT) applications assume that data will be moved offdevices into centralized cloud platforms. While existing IoT systems leverage cloud-based analytics for meaningful data reasoning, the assumption that data should always be moved off the devices is problematic. The amount of data to be moved...
The trend towards higher resolution, faster refresh rate active-matrix liquid-crystal displays (AMLCDs) as well as the emergence of active-matrix organic light-emitting diode (AMOLED) displays is driving the demand for amorphous oxide semiconductor thin-film transistors (AOS TFTs) with higher mobility. A physics-based model for carrier transport in an amorphous semiconductor is...
The electrical stability of amorphous indium-gallium-zinc oxide (a-IGZO) thinfilmtransistors (TFTs) is investigated for flat-panel display applications. Althoughproducts incorporating a-IGZO TFT backplanes are already commercially available,e.g., iMac with 5K retina display, technical challenges need to be addressed for nextgenerationapplications, e.g., active-matrix organic light-emitting diode displays.Device stability is one crucial issue. The...
The internet-of-things is a growing market segment which is based on an arrayof portable communication devices with high power efficiency. Advanced semiconductortechnology can easily improve their digital performance, but the samecannot be said for the analog blocks which are vital to their operation. Highperformance analog circuits continue to use conventional...
Energy consumption has become a great deal for cloud service providers due to financial as well as environmental concerns. Studies show that cloud servers operate, most of the time, at only between 10% and 50% of their maximal utilizations. These same studies also show that servers that are kept ON...
Cognitive radio technology emerges as a promising solution for overcoming shortage and inefficient use of spectrum resources. In cognitive radio networks, secondary users, which are users equipped with cognitive radios, can opportunistically access spectrum assigned to primary users, the spectrum license holders. Although it improves spectrum utilization efficiency, this opportunistic...
The rapid scaling of network bandwidth and data center throughput has motivated the wide adoption of high speed transceivers. Silicon photonics (Si-Photonic) is one of the most promising techniques to realize tightly integrated optical transceivers for next-generation high speed I O standards. This dissertation focuses on the design techniques of...
Back end of line (BEOL) metal-insulator-metal capacitors (MIMCAPs) have become a core passive component in modern integrated circuits. International Technology Roadmap for Semiconductors (ITRS) projections for scaling of analog/mixed-signal MIMCAP applications require simultaneously increasing capacitance density while maintaining low leakage current density and low voltage nonlinearity (characterized by the quadratic...
Triangulateration uses geometric distance to estimate the location of user by employing techniques like received signal strength (RSS), time-of-arrival (TOA), time-difference-of-arrival (TDOA) and image processing.
Radio frequency (RF) signal positioning using TOA or TDOA techniques generally requires timing synchronization of the anchors and/or the anchors and targets. If the desired...
Wireless power transfer (WPT) is a way to transfer power from one device to another without any wire or cable connections. Although the technology has been around for more than 100 years, it is gaining popularity in recent years due to the ever-increasing demand for faster and more frequent charging...