ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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- Creators: Bakkaloglu, Bertan
Description
Power management circuits have been more and more widely used in various applications, while providing fully integrated voltage regulation remains a challenging topic. Switched-capacitor (SC) voltage converters have received attentions in integrated power conversion for fixed-ratio voltage conversions with good efficiency and feasibility of integration. During my PhD study, an on-chip current sensing technique is proposed to dynamically modulate both switching frequency and switch widths of SC voltage converters, enhancing fast transient response and higher efficiency across a wide range of load currents. In conjunction with SC converters, a low-dropout regulator (LDO) is implemented which is driven by a push-pull operational transconductance amplifier (OTA), whose current is mirrored and sensed with minimal power and efficiency overhead. The sensed load current directly controls the frequency and width of SC converters through a voltage-controlled oscillator (VCO) and a time-to-digital converter, respectively.
Theoretical analysis and optimization for SC DC-DC converters have been presented in prior works, however optimization of different capacitors, namely flying and input/output decoupling capacitors, in SC voltage regulators (SCVRs) under an area constraint has not been addressed. A methodology to optimize flying and decoupling capacitance for area-constrained on-chip SCVRs to achieve the highest system-level power efficiency. Considering both conversion efficiency and droop voltage against fast load transients, the proposed model determines the optimal ratio between flying and decoupling.
Based on the previous design, a fully integrated switched-capacitor voltage regulator with voltage comparison and on-chip lossless current sensing control is proposed. Based on the voltage comparison result and sensed current as the load current changes, the frequency of the SC converters are modulated for optimal efficiency. The voltage regulator targets 2.1V input voltage and 0.9V output voltage, which offers higher-voltage power transfer across chip package. A 17-phase interleaved structure is used to reduce output voltage ripple.
In 65nm CMOS, the regulator is implemented with MIM-capacitor, targeting 2.1V input voltage and 0.9V output voltage. According to the measurement results, the proposed SC voltage regulator achieves 69.6% peak efficiency at 60mA load current, which corresponds to a 4.2mW/mm2 power-area density and 12.5mW
F power-capacitance density. The efficiency across 20mA to 92mA regulator load current range is above 62%. The steady-state output voltage ripple across 22x load current range of 3.5mA-76mA is between 50mV to 60mV.
Theoretical analysis and optimization for SC DC-DC converters have been presented in prior works, however optimization of different capacitors, namely flying and input/output decoupling capacitors, in SC voltage regulators (SCVRs) under an area constraint has not been addressed. A methodology to optimize flying and decoupling capacitance for area-constrained on-chip SCVRs to achieve the highest system-level power efficiency. Considering both conversion efficiency and droop voltage against fast load transients, the proposed model determines the optimal ratio between flying and decoupling.
Based on the previous design, a fully integrated switched-capacitor voltage regulator with voltage comparison and on-chip lossless current sensing control is proposed. Based on the voltage comparison result and sensed current as the load current changes, the frequency of the SC converters are modulated for optimal efficiency. The voltage regulator targets 2.1V input voltage and 0.9V output voltage, which offers higher-voltage power transfer across chip package. A 17-phase interleaved structure is used to reduce output voltage ripple.
In 65nm CMOS, the regulator is implemented with MIM-capacitor, targeting 2.1V input voltage and 0.9V output voltage. According to the measurement results, the proposed SC voltage regulator achieves 69.6% peak efficiency at 60mA load current, which corresponds to a 4.2mW/mm2 power-area density and 12.5mW
F power-capacitance density. The efficiency across 20mA to 92mA regulator load current range is above 62%. The steady-state output voltage ripple across 22x load current range of 3.5mA-76mA is between 50mV to 60mV.
ContributorsMi, Xiaoyang (Author) / Seo, Jae-Sun (Thesis advisor) / Bakkaloglu, Bertan (Committee member) / Ogras, Umit Y. (Committee member) / Kitchen, Jennifer (Committee member) / Arizona State University (Publisher)
Created2020
Description
Nearly all solar photovoltaic (PV) systems are designed with maximum power point tracking (MPPT) functionality to maximize the utilization of available power from the PV array throughout the day. In conventional PV systems, the MPPT function is handled by a power electronic device, like a DC-AC inverter. However, given that most PV systems are designed to be grid-connected, there are several challenges for designing PV systems for DC-powered applications and off-grid applications. The first challenge is that all power electronic devices introduce some degree of power loss. Beyond the cost of the lost power, the upfront cost of power electronics also increases with the required power rating. Second, there are very few commercially available options for DC-DC converters that include MPPT functionality, and nearly all PV inverters are designed as “grid-following” devices, as opposed to “grid-forming” devices, meaning they cannot be used in off-grid applications.
To address the challenges of designing PV systems for high-power DC and off-grid applications, a load-managing photovoltaic (LMPV) system topology has been proposed. Instead of using power electronics, the LMPV system performs maximum power point tracking through load management. By implementing a load-management approach, the upfront costs and the power losses associated with the power electronics are avoided, both of which improve the economic viability of the PV system. This work introduces the concept of an LMPV system, provides in-depth analyses through both simulation and experimental validation, and explores several potential applications of the system, such as solar-powered commercial-scale electrolyzers for the production of hydrogen fuel or the production and purification of raw materials like caustic soda, copper, and zinc.
To address the challenges of designing PV systems for high-power DC and off-grid applications, a load-managing photovoltaic (LMPV) system topology has been proposed. Instead of using power electronics, the LMPV system performs maximum power point tracking through load management. By implementing a load-management approach, the upfront costs and the power losses associated with the power electronics are avoided, both of which improve the economic viability of the PV system. This work introduces the concept of an LMPV system, provides in-depth analyses through both simulation and experimental validation, and explores several potential applications of the system, such as solar-powered commercial-scale electrolyzers for the production of hydrogen fuel or the production and purification of raw materials like caustic soda, copper, and zinc.
ContributorsAzzolini, Joseph Anthony (Author) / Tao, Meng (Thesis advisor) / Bakkaloglu, Bertan (Committee member) / Qin, Jiangchao (Committee member) / Reno, Matthew J. (Committee member) / Arizona State University (Publisher)
Created2020
Description
Modern Communication systems are progressively moving towards all-digital transmitters (ADTs) due to their high efficiency and potentially large frequency range. While significant work has been done on individual blocks within the ADT, there are few to no full systems designs at this point in time. The goal of this work is to provide a set of multiple novel block architectures which will allow for greater cohesion between the various ADT blocks. Furthermore, the design of these architectures are expected to focus on the practicalities of system design, such as regulatory compliance, which here to date has largely been neglected by the academic community. Amongst these techniques are a novel upconverted phase modulation, polyphase harmonic cancellation, and process voltage and temperature (PVT) invariant Delta Sigma phase interpolation. It will be shown in this work that the implementation of the aforementioned architectures allows ADTs to be designed with state of the art size, power, and accuracy levels, all while maintaining PVT insensitivity. Due to the significant performance enhancement over previously published works, this work presents the first feasible ADT architecture suitable for widespread commercial deployment.
ContributorsGrout, Kevin Samuel (Author) / Kitchen, Jennifer N (Thesis advisor) / Khalil, Waleed (Committee member) / Bakkaloglu, Bertan (Committee member) / Aberle, James T., 1961- (Committee member) / Garrity, Douglas (Committee member) / Arizona State University (Publisher)
Created2019
Description
This thesis presents three novel studies. The first two works focus on galvanically isolated chip-to-chip communication, and the third research studies class-E pulse-width modulated power amplifiers. First, a common-mode resilient CMOS (complementary metal-oxide-semiconductor) galvanically isolated Radio Frequency (RF) chip-to-chip communication system is presented utilizing laterally resonant coupled circuits to increases maximum common-mode transient immunity and the isolation capability of galvanic isolators in a low-cost standard CMOS solution beyond the limits provided from the vertical coupling. The design provides the highest reported CMTI (common-mode transient immunity) of more than 600 kV/µs, 5 kVpk isolation, and a chip area of 0.95 mm2. In the second work, a bi-directional ultra-wideband transformer-coupled galvanic isolator is reported for the first time. The proposed design merges the functionality of two isolated channels into one magnetically coupled communication, enabling up to 50% form-factor and assembly cost reduction while achieving a simultaneously robust and state-of-art performance. This work achieves simultaneous robust, wideband, and energy-efficient performance of 300 Mb/s data rate, isolation of 7.8 kVrms, and power consumption and propagation delay of 200 pJ/b and 5 ns, respectively, in only 0.8 mm2 area. The third works studies class-E pulse-width modulated (PWM) Power amplifiers (PAs). For the first time, it presents a design technique to significantly extend the Power back-off (PBO) dynamic range of PWM PAs over the prior art. A proof-of-concept watt-level class-E PA is designed using a GaN HEMT and exhibits more than 6dB dynamic range for a 50 to 30 percent duty cycle variation. Moreover, in this work, the effects of non-idealities on performance and design of class-E power amplifiers for variable supply on and pulse-width operations are characterized and studied, including the effect of non-linear parasitic capacitances and its exploitation for enhancement of average efficiency and self-heating effects in class-E SMPAs using a new over dry-ice measurement technique was presented for this first time. The non-ideality study allows for capturing a full view of the design requirement and considerations of class-E power amplifiers and provides a window to the phenomena that lead to a mismatch between the ideal and actual performance of class-E power amplifiers and their root causes.
ContributorsJavidahmadabadi, Mahdi (Author) / Kitchen, Jennifer N (Thesis advisor) / Aberle, James (Committee member) / Bakkaloglu, Bertan (Committee member) / Burton, Richard (Committee member) / Arizona State University (Publisher)
Created2021
Description
ABSTRACT As the technology length shrinks down, achieving higher gain is becoming very difficult in deep sub-micron technologies. As the supply voltages drop, cascodes are very difficult to implement and cascade amplifiers are needed to achieve sufficient gain with required output swing. This sets the fundamental limit on the SNR and hence the maximum resolution that can be achieved by ADC. With the RSD algorithm and the range overlap, the sub ADC can tolerate large comparator offsets leaving the linearity and accuracy requirement for the DAC and residue gain stage. Typically, the multiplying DAC requires high gain wide bandwidth op-amp and the design of this high gain op-amp becomes challenging in the deep submicron technologies. This work presents `A 12 bit 25MSPS 1.2V pipelined ADC using split CLS technique' in IBM 130nm 8HP process using only CMOS devices for the application of Large Hadron Collider (LHC). CLS technique relaxes the gain requirement of op-amp and improves the signal-to-noise ratio without increase in power or input sampling capacitor with rail-to-rail swing. An op-amp sharing technique has been incorporated with split CLS technique which decreases the number of op-amps and hence the power further. Entire pipelined converter has been implemented as six 2.5 bit RSD stages and hence decreases the latency associated with the pipelined architecture - one of the main requirements for LHC along with the power requirement. Two different OTAs have been designed to use in the split-CLS technique. Bootstrap switches and pass gate switches are used in the circuit along with a low power dynamic kick-back compensated comparator.
ContributorsSwaminathan, Visu Vaithiyanathan (Author) / Barnaby, Hugh (Thesis advisor) / Bakkaloglu, Bertan (Committee member) / Christen, Jennifer Blain (Committee member) / Arizona State University (Publisher)
Created2012
Description
Impedance is one of the fundamental properties of electrical components, materials, and waves. Therefore, impedance measurement and monitoring have a wide range of applications. The multi-port technique is a natural candidate for impedance measurement and monitoring due to its low overhead and ease of implementation for Built-in Self-Test (BIST) applications. The multi-port technique can measure complex reflection coefficients, thus impedance, by using scalar measurements provided by the power detectors. These power detectors are strategically placed on different points (ports) of a passive network to produce unique solution. Impedance measurement and monitoring is readily deployed on mobile phone radio-frequency (RF) front ends, and are combined with antenna tuners to boost the signal reception capabilities of phones. These sensors also can be used in self-healing circuits to improve their yield and performance under process, voltage, and temperature variations. Even though, this work is preliminary interested in low-overhead impedance measurement for RF circuit applications, the proposed methods can be used in a wide variety of metrology applications where impedance measurements are already used. Some examples of these applications include determining material properties, plasma generation, and moisture detection. Additionally, multi-port applications extend beyond the impedance measurement. There are applications where multi-ports are used as receivers for communication systems, RADARs, and remote sensing applications. The multi-port technique generally requires a careful design of the testing structure to produce a unique solution from power detector measurements. It also requires the use of nonlinear solvers during calibration, and depending on calibration procedure, measurement. The use of nonlinear solvers generates issues for convergence, computational complexity, and resources needed for carrying out calibrations and measurements in a timely manner. In this work, using periodic structures, a structure where a circuit block repeats itself, for multi-port measurements is proposed. The periodic structures introduce a new constraint that simplifies the multi-port theory and leads to an explicit calibration and measurement procedure. Unlike the existing calibration procedures which require at least five loads and various constraints on the load for explicit solution, the proposed method can use three loads for calibration. Multi-ports built with periodic structures will always produce a unique measurement result. This leads to increased bandwidth of operation and simplifies design procedure. The efficacy of the method demonstrated in two embodiments.
In the first embodiment, a multi-port is directly embedded into a matching network to measure impedance of the load.
In the second embodiment, periodic structures are used to compare two loads without requiring any calibration.
ContributorsAvci, Muslum Emir (Author) / Ozev, Sule (Thesis advisor) / Bakkaloglu, Bertan (Committee member) / Kitchen, Jennifer (Committee member) / Trichopoulos, Georgios (Committee member) / Arizona State University (Publisher)
Created2023
Description
This work presents two balanced power amplifier (PA) architectures, one at X-band and the other at K-band. The presented balanced PAs are designed for use in small satellite and cube satellite applications.The presented X-band PA employs wideband hybrid couplers to split input power to two commercial off-the-shelf (COTS) Gallium Nitride (GaN) monolithic microwave integrated circuit (MMIC) PAs and combine their output powers. The presented X-band balanced PA manufactured on a Rogers 4003C substrate yields increased small signal gain and saturated output power under continuous wave (CW) operation compared to the single MMIC PA used in the design under pulsed operation. The presented PA operates from 7.5 GHz to 11.5 GHz, has a maximum small signal gain of 36.3 dB, a maximum saturated power out of 40.0 dBm, and a maximum power added efficiency (PAE) of 38%.
Both a Wilkinson and a Gysel splitter and combiner are designed for use at K-band and their performance is compared. The presented K-band balanced PA uses Gysel power dividers and combiners with a GaN MMIC PA that is soon to be released in production.
ContributorsPearson, Katherine Elizabeth (Author) / Kitchen, Jennifer (Thesis advisor) / Bakkaloglu, Bertan (Committee member) / Ozev, Sule (Committee member) / Arizona State University (Publisher)
Created2023
Description
In this dissertation, enhanced coherent detection of terahertz (THz) radiation is presented for Silicon integrated circuits (ICs). In general THz receivers implemented in silicon technologies face a challenge due to the high noise figure (NF) of the low noise amplifier (LNA) and low conversion gain of the radio frequency (RF) mixers. Moreover, issues with implementing local oscillators (LOs) further compound these challenges, including power driving mixes, distribution networks, and overall power consumption, particularly for large-scale arrays. To address these inherent obstacles, two notable cases of enhancing THz receiver performance are presented. In the Sideband Separation Receiver (SSR) for space-borne applications is introduced. Implemented in SiGe BiCMOS technology this broadband SSR boasts a high Image Rejection Ratio (IRR) exceeding 20 dB across 220 – 320 GHz. Employing a modified Weaver architecture, optimized for simultaneous spectral line observation, it utilizes an I/Q double down-conversion, pushing the technological boundaries of silicon and enabling large-scale focal plane array (FPA) deployment in space. Notably, the use of a sub-harmonic down-conversion mixer (SHM) significantly reduces LO power generation challenges, enhancing scalability while maintaining minimal NF.
In the 4x4 FPA active THz imager, a dual-polarized patch antenna operating at 420 GHz utilizes orthogonal polarization for RF and LO signals, coupled with a coherent homodyne power detector. Realized in 0.13µm SiGe HBT technology, the power detector is co-designing with the antenna to ensure minimal crosstalk and achieving -30dB cross-polarization isolation. Illumination of the LO enhances power detector performance without on-chip routing complexities, enabling scalability to 1K pixel THz imagers. Each pixel achieves a Noise-Equivalent Power (NEP) of 1 pW/√Hz at 420 GHz, and integration with a readout and digital filter ensures high dynamic range.
Furthermore, this study explores radiation hardening techniques to mitigate single-event effects (SEEs) in high-frequency receivers operating in space. Leveraging a W-band receiver in 90 nm SiGe BiCMOS technology, matching considerations and diverse modes of operation are employed to reduce SEE susceptibility. Transient current pulse modeling, validated through TCAD simulations, demonstrates the effectiveness of proposed techniques in substantially mitigating SETs within the proposed radiation-hardened-by-design (RHBD) receiver front-end.
ContributorsAl Seragi, Ebrahim (Author) / Zeinolabedinzadeh, Saeed (Thesis advisor) / Trichopoulos, Georgios (Committee member) / Bakkaloglu, Bertan (Committee member) / Aberle, James (Committee member) / Kitchen, Jennifer (Committee member) / Arizona State University (Publisher)
Created2024
Description
Recent advancements in communication standards, such as 5G demand transmitter hardware to support high data rates with high energy efficiency. With the revolution of communication standards, modulation schemes have become more complex and require high peak-to-average (PAPR) signals. In wireless transceiver hardware, the power amplifier (PA) consumes most of the transceiver’s DC power and is typically the bottleneck for transmitter linearity. Therefore, the transmitter’s performance directly depends on the PA. To support high PAPR signals, the PA must operate efficiently at its saturated and backoff output power. Maintaining high efficiency at both peak and backoff output power is challenging. One effective technique for addressing this problem is load modulation. Some of the prominent load-modulated PA architectures are outphasing PAs, load-modulated balanced amplifiers (LMBA), envelope elimination and restoration (EER), envelope tracking (ET), Doherty power amplifiers (DPA), and polar transmitters. Amongst them, the DPA is the most popular for infrastructure applications due to its simpler architecture compared to other techniques and linearizability with digital pre-distortion (DPD). Another crucial characteristic of progressing communication standards is wide signal bandwidths. High-efficiency power amplifiers like class J/F/F-1 and load-modulated PAs like the DPA exhibit narrowband performance because the amplifiers require precise output impedance terminations. Therefore, it is equally essential to develop adaptable PA solutions to process radio frequency (RF) signals with wide bandwidths. To support modern and future cellular infrastructure, RF PAs need to be innovated to increase the backoff power efficiency by two times or more and support ten times or more wider bandwidths than current state-of-the-art PAs. This work presents five RF PA analyses and implementations to support future wireless communications transmitter hardware. Chapter 2 presents an optimized output-matching network analysis and design to achieve extended output power backoff of the DPA. Chapters 3 and 4 unveil two bandwidth enhancement techniques for the DPA while maintaining extended output power backoff. Chapter 5 exhibits a dual-band hybrid mode PA design targeted for wideband applications. Chapter 6 presents a built-in self-test circuit integrated into a PA for output impedance monitoring. This can alleviate the PA performance degradation due to the variation in the PA's output load over frequency, process, and aging. All RF PAs in this dissertation are implemented using Gallium Nitride (GaN)-based high electron mobility transistors (HEMT), and the realized designs validate the proposed PAs' theories/architectures.
ContributorsRoychowdhury, Debatrayee (Author) / Kitchen, Jennifer (Thesis advisor) / Bakkaloglu, Bertan (Committee member) / Ozev, Sule (Committee member) / Aberle, James (Committee member) / Arizona State University (Publisher)
Created2024
Description
The world has seen a revolution in cellular communication with the advent of 5G (fifth-generation), which enables gigabits per second data speed with low latency, massive capacity, and increased availability. These modern wireless systems improve spectrum efficiency by employing advanced modulation techniques, but result in large peak-to-average power ratios (PAPR) of the transmitted signals that degrades the efficiency of the radio-frequency power amplifiers (PAs) in the power back-off (PBO) region. Envelope tracking (ET), which is a dynamic supply control technology to realize high efficiency PAs, is a promising approach for designing transmitters for the future. Conventional voltage regulators, such as linear regulators and switching regulators, fail to simultaneously offer high speed, high efficiency, and improved linearity. Hybrid supply modulators (HSM) that combine a linear and switching regulator emerge as promising solutions to achieve an optimized tradeoff between different design parameters. Over the years, considerable development and research efforts in industry and academia have been spent on maximizing HSM performance, and a majority of the most recently developed modulators are implemented in CMOS technology and mainly targeted for handset applications. In this dissertation, the main requirements for modern HSM designs are categorized and analyzed in detail. Next, techniques to improve HSM performance are discussed. The available device technologies for HSM and PA implementations are also delineated, and implementation challenges of an integrated ET-PA system are summarized. Finally, a Current-Mode with Dynamic Hysteresis HSM is proposed, designed, and implemented. With the proposed technique, the HSM is able to track LTE signals up to 100 MHz bandwidth. Switching at a peak frequency of 40 MHz, the design is able to track a 1 Vpp sinusoidal signal with high fidelity, has an output voltage ripple around 54 mV, and achieves a peak static and dynamic efficiency of 92.2% and 82.29%, respectively, at the maximum output. The HSM is capable of delivering a maximum output power of 425 mW and occupies a small die area of 1.6mm2. Overall, the proposed HSM promises competitive performance compared to state-of-the-art works.
ContributorsBHARDWAJ, SUMIT (Author) / Kitchen, Jennifer (Thesis advisor) / Ozev, Sule (Committee member) / Bakkaloglu, Bertan (Committee member) / Singh, Shrikant (Committee member) / Arizona State University (Publisher)
Created2024