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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.


Contributor
Date Range
2010 2018


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 ...

Contributors
Swaminathan, Visu Vaithiyanathan, Barnaby, Hugh, Bakkaloglu, Bertan, et al.
Created Date
2012

Pulse Density Modulation- (PDM-) based class-D amplifiers can reduce non-linearity and tonal content due to carrier signal in Pulse Width Modulation - (PWM-) based amplifiers. However, their low-voltage analog implementations also require a linear- loop filter and a quantizer. A PDM-based class-D audio amplifier using a frequency-domain quantization is presented in this paper. The digital-intensive frequency domain approach achieves high linearity under low-supply regimes. An analog comparator and a single-bit quantizer are replaced with a Current-Controlled Oscillator- (ICO-) based frequency discriminator. By using the ICO as a phase integrator, a third-order noise shaping is achieved using only two analog integrators. ...

Contributors
Lee, Junghan, Bakkaloglu, Bertan, Kiaei, Sayfe, et al.
Created Date
2011

Voltage Control Oscillator (VCO) is one of the most critical blocks in Phase Lock Loops (PLLs). LC-tank VCOs have a superior phase noise performance, however they require bulky passive resonators and often calibration architectures to overcome their limited tuning range. Ring oscillator (RO) based VCOs are attractive for digital technology applications owing to their ease of integration, small die area and scalability in deep submicron processes. However, due to their supply sensitivity and poor phase noise performance, they have limited use in applications demanding low phase noise floor, such as wireless or optical transceivers. Particularly, out-of-band phase noise of RO-based ...

Contributors
Min, Seungkee, Kiaei, Sayfe, Bakkaloglu, Bertan, et al.
Created Date
2011

The front end of almost all ADCs consists of a Sample and Hold Circuit in order to make sure a constant analog value is digitized at the end of ADC. The design of Track and Hold Circuit (THA) mainly focuses on following parameters: Input frequency, Sampling frequency, dynamic Range, hold pedestal, feed through error. This thesis will discuss the importance of these parameters of a THA to the ADCs and commonly used architectures of THA. A new architecture with SiGe HBT transistors in BiCMOS 130 nm technology is presented here. The proposed topology without complicated circuitry achieves high Spurious Free ...

Contributors
Ramakrishna Rao, Nishita Ramakrishna, Barnaby, Hugh, Bakkaloglu, Bertan, et al.
Created Date
2012

Phase locked loops are an integral part of any electronic system that requires a clock signal and find use in a broad range of applications such as clock and data recovery circuits for high speed serial I/O and frequency synthesizers for RF transceivers and ADCs. Traditionally, PLLs have been primarily analog in nature and since the development of the charge pump PLL, they have almost exclusively been analog. Recently, however, much research has been focused on ADPLLs because of their scalability, flexibility and higher noise immunity. This research investigates some of the latest all-digital PLL architectures and discusses the qualities ...

Contributors
Zazzera, Joshua, Bakkaloglu, Bertan, Bakkaloglu, Bertan, et al.
Created Date
2012

Fluxgate sensors are magnetic field sensors that can measure DC and low frequency AC magnetic fields. They can measure much lower magnetic fields than other magnetic sensors like Hall effect sensors, magnetoresistive sensors etc. They also have high linearity, high sensitivity and low noise. The major application of fluxgate sensors is in magnetometers for the measurement of earth's magnetic field. Magnetometers are used in navigation systems and electronic compasses. Fluxgate sensors can also be used to measure high DC currents. Integrated micro-fluxgate sensors have been developed in recent years. These sensors have much lower power consumption and area compared to ...

Contributors
Pappu, Karthik, Bakkaloglu, Bertan, Christen, Jennifer Blain, et al.
Created Date
2013

This thesis presents a gas sensor readout IC for amperometric and conductometric electrochemical sensors. The Analog Front-End (AFE) readout circuit enables tracking long term exposure to hazardous gas fumes in diesel and gasoline equipments, which may be correlated to diseases. Thus, the detection and discrimination of gases using microelectronic gas sensor system is required. This thesis describes the research, development, implementation and test of a small and portable based prototype platform for chemical gas sensors to enable a low-power and low noise gas detection system. The AFE reads out the outputs of eight conductometric sensor array and eight amperometric sensor ...

Contributors
Kim, Hyuntae, Bakkaloglu, Bertan, Vermeire, Bert, et al.
Created Date
2011

During the last decades the development of the transistor and its continuous down-scaling allowed the appearance of cost effective wireless communication systems. New generation wideband wireless mobile systems demand high linearity, low power consumption and the low cost devices. Traditional RF systems are mainly analog-based circuitry. Contrary to digital circuits, the technology scaling results in reduction on the maximum voltage swing which makes RF design very challenging. Pushing the interface between the digital and analog boundary of the RF systems closer to the antenna becomes an attractive trend for modern RF devices. In order to take full advantages of the ...

Contributors
Han, Yongping, Kiaei, Sayfe, Yu, Hongyu, et al.
Created Date
2012

Sliding-Mode Control (SMC) has several benefits over traditional Proportional-Integral-Differential (PID) control in terms of fast transient response, robustness to parameter and component variations, and low sensitivity to loop disturbances. An All-Digital Sliding-Mode (ADSM) controlled DC-DC converter, utilizing single-bit oversampled frequency domain digitizers is proposed. In the proposed approach, feedback and reference digitizing Analog-to-Digital Converters (ADC) are based on a single-bit, first order Sigma-Delta frequency to digital converter, running at 32MHz over-sampling rate. The ADSM regulator achieves 1% settling time in less than 5uSec for a load variation of 600mA. The sliding-mode controller utilizes a high-bandwidth hysteretic differentiator and an integrator ...

Contributors
Dashtestani, Ahmad, Bakkaloglu, Bertan, Thornton, Trevor, et al.
Created Date
2013

Switching Converters (SC) are an excellent choice for hand held devices due to their high power conversion efficiency. However, they suffer from two major drawbacks. The first drawback is that their dynamic response is sensitive to variations in inductor (L) and capacitor (C) values. A cost effective solution is implemented by designing a programmable digital controller. Despite variations in L and C values, the target dynamic response can be achieved by computing and programming the filter coefficients for a particular L and C. Besides, digital controllers have higher immunity to environmental changes such as temperature and aging of components. The ...

Contributors
Mumma Reddy, Abhiram, Bakkaloglu, Bertan, Ogras, Umit, et al.
Created Date
2014

Switching regulator has several advantages over linear regulator, but the drawback of switching regulator is ripple voltage on output. Previously people use LDO following a buck converter and multi-phase buck converter to reduce the output voltage ripple. However, these two solutions also have obvious drawbacks and limitations. In this thesis, a novel mixed signal adaptive ripple cancellation technique is presented. The idea is to generate an artificial ripple current with the same amplitude as inductor current ripple but opposite phase that has high linearity tracking behavior. To generate the artificial triangular current, duty cycle information and inductor current ripple amplitude ...

Contributors
Yang, Zhe, Bakkaloglu, Bertan, Seo, Jae-sun, et al.
Created Date
2016

Residue number systems have gained significant importance in the field of high-speed digital signal processing due to their carry-free nature and speed-up provided by parallelism. The critical aspect in the application of RNS is the selection of the moduli set and the design of the conversion units. There have been several RNS moduli sets proposed for the implementation of digital filters. However, some are unbalanced and some do not provide the required dynamic range. This thesis addresses the drawbacks of existing RNS moduli sets and proposes a new moduli set for efficient implementation of FIR filters. An efficient VLSI implementation ...

Contributors
Chalivendra, Gayathri, Vrudhula, Sarma, Shrivastava, Aviral, et al.
Created Date
2011

In this work, the development of a novel and a truly in-shoe force measurement system is reported. The device consists of a shoe insole with six thin film piezoresistive sensors and the main circuit board. The piezoresistive sensors are used for the measurement of plantar pressure during daily human activities. The motion sensor mounted on the main circuit board captures kinematic data. In addition, the main circuit board is responsible for the wireless transmission of the data from all the sensors in real-time using BLE protocol. It is housed within the midsole of the shoe, under the medial arch of ...

Contributors
Badarinath, Abhishek, Kiaei, Sayfe, Bakkaloglu, Bertan, et al.
Created Date
2018

The non-quasi-static (NQS) description of device behavior is useful in fast switching and high frequency circuit applications. Hence, it is necessary to develop a fast and accurate compact NQS model for both large-signal and small-signal simulations. A new relaxation-time-approximation based NQS MOSFET model, consistent between transient and small-signal simulations, has been developed for surface-potential-based MOSFET compact models. The new model is valid for all regions of operation and is compatible with, and at low frequencies recovers, the quasi-static (QS) description of the MOSFET. The model is implemented in two widely used circuit simulators and tested for speed and convergence. It ...

Contributors
Zhu, Zeqin, Gildenblat, Gennady, Bakkaloglu, Bertan, et al.
Created Date
2012

Traditional wireless communication systems operate in duplexed modes i.e. using time division duplexing or frequency division duplexing. These methods can respectively emulate full duplex mode operation or realize full duplex mode operation with decreased spectral efficiency. This thesis presents a novel method of achieving full duplex operation by actively cancelling out the transmitted signal in pseudo-real time. With appropriate hardware, the algorithms and techniques used in this work can be implemented in real time without any knowledge of the channel or any training sequence. Convergence times of down to 1 ms can be achieved which is adequate for the coherence ...

Contributors
Avasarala, Sanjay, Kiaei, Sayfe, Kitchen, Jennifer, et al.
Created Date
2016

A dual-channel directional digital hearing aid (DHA) front end using Micro Electro Mechanical System (MEMS) microphones and an adaptive-power analog processing signal chain is presented. The analog front end consists of a double differential amplifier (DDA) based capacitance to voltage conversion circuit, 40dB variable gain amplifier (VGA) and a continuous time sigma delta analog to digital converter (CT - ΣΔ ADC). Adaptive power scaling of the 4th order CT - ΣΔ achieves 68dB SNR at 120μW, which can be scaled down to 61dB SNR at 67μW. This power saving will increse the battery life of the DHA. Dissertation/Thesis

Contributors
Deligoz, Ilker, Kiaei, Sayfe, Bakkaloglu, Bertan, et al.
Created Date
2010

Presently, hard-switching buck/boost converters are dominantly used for automotive applications. Automotive applications have stringent system requirements for dc-dc converters, such as wide input voltage range and limited EMI noise emission. High switching frequency of the dc-dc converters is much desired in automotive applications for avoiding AM band interference and for compact size. However, hard switching buck converter is not suitable at high frequency operation because of its low efficiency. In addition, buck converter has high EMI noise due to its hard-switching. Therefore, soft-switching topologies are considered in this thesis work to improve the performance of the dc-dc converters. Many soft-switching ...

Contributors
Nan, Chenhao, Ayyanar, Raja, Bakkaloglu, Bertan, et al.
Created Date
2016

Negative bias temperature instability (NBTI) and channel hot carrier (CHC) are important reliability issues impacting analog circuit performance and lifetime. Compact reliability models and efficient simulation methods are essential for circuit level reliability prediction. This work proposes a set of compact models of NBTI and CHC effects for analog and mixed-signal circuit, and a direct prediction method which is different from conventional simulation methods. This method is applied in circuit benchmarks and evaluated. This work helps with improving efficiency and accuracy of circuit aging prediction. Dissertation/Thesis

Contributors
Zheng, Rui, Cao, Yu, Yu, Hongyu, et al.
Created Date
2011

Process variations have become increasingly important for scaled technologies starting at 45nm. The increased variations are primarily due to random dopant fluctuations, line-edge roughness and oxide thickness fluctuation. These variations greatly impact all aspects of circuit performance and pose a grand challenge to future robust IC design. To improve robustness, efficient methodology is required that considers effect of variations in the design flow. Analyzing timing variability of complex circuits with HSPICE simulations is very time consuming. This thesis proposes an analytical model to predict variability in CMOS circuits that is quick and accurate. There are several analytical models to estimate ...

Contributors
Gummalla, Samatha, Chakrabarti, Chaitali, Cao, Yu, et al.
Created Date
2011

Micro Electro Mechanical Systems (MEMS) is one of the fastest growing field in silicon industry. Low cost production is key for any company to improve their market share. MEMS testing is challenging since input to test a MEMS device require physical stimulus like acceleration, pressure etc. Also, MEMS device vary with process and requires calibration to make them reliable. This increases test cost and testing time. This challenge can be overcome by combining electrical stimulus based testing along with statistical analysis on MEMS response for electrical stimulus and also limited physical stimulus response data. This thesis proposes electrical stimulus based ...

Contributors
Kundur, Vinay, Bakkaloglu, Bertan, Ozev, Sule, et al.
Created Date
2013

Testing and calibration constitute a significant part of the overall manufacturing cost of microelectromechanical system (MEMS) devices. Developing a low-cost testing and calibration scheme applicable at the user side that ensures the continuous reliability and accuracy is a crucial need. The main purpose of testing is to eliminate defective devices and to verify the qualifications of a product is met. The calibration process for capacitive MEMS devices, for the most part, entails the determination of the mechanical sensitivity. In this work, a physical-stimulus-free built-in-self-test (BIST) integrated circuit (IC) design characterizing the sensitivity of capacitive MEMS accelerometers is presented. The BIST ...

Contributors
Ozel, Muhlis Kenan, Bakkaloglu, Bertan, Ozev, Sule, et al.
Created Date
2017

High-efficiency DC-DC converters make up one of the important blocks of state-of-the-art power supplies. The trend toward high level of transistor integration has caused load current demands to grow significantly. Supplying high output current and minimizing output current ripple has been a driving force behind the evolution of Multi-phase topologies. Ability to supply large output current with improved efficiency, reduction in the size of filter components, improved transient response make multi-phase topologies a preferred choice for low voltage-high current applications. Current sensing capability inside a system is much sought after for applications which include Peak-current mode control, Current limiting, Overload ...

Contributors
Burli, Venkatesh, Bakkaloglu, Bertan, Garrity, Douglas, et al.
Created Date
2017

Radiation hardening by design (RHBD) has become a necessary practice when creating circuits to operate within radiated environments. While employing RHBD techniques has tradeoffs between size, speed and power, novel designs help to minimize these penalties. Space radiation is the primary source of radiation errors in circuits and two types of single event effects, single event upsets (SEU), and single event transients (SET) are increasingly becoming a concern. While numerous methods currently exist to nullify SEUs and SETs, special consideration to the techniques of temporal hardening and interlocking are explored in this thesis. Temporal hardening mitigates both SETs and SEUs ...

Contributors
Matush, Bradley, Clark, Lawrence T, Allee, David, et al.
Created Date
2010

In this dissertation a new wideband circular HIS is proposed. The circular periodicity made it possible to illuminate the surface with a cylindrical TEMz wave and; a novel technique is utilized to make it wideband. Two models are developed to analyze the reflection characteristics of the proposed HIS. The circularly symmetric high impedance surface is used as a ground plane for the design of a low-profile loop and spiral radiating elements. It is shown that a HIS with circular periodicity provides a wider operational bandwidth for curvilinear radiating elements such, such as loops and spirals, compared to canonical rectangular HISs. ...

Contributors
Amiri, Mikal Askarian, Balanis, Constantine A, Aberle, James T, et al.
Created Date
2018

High Impedance Surfaces (HISs), which have been investigated extensively, have proven to be very efficient ground planes for low profile antenna applications due to their unique reflection phase characteristics. Another emerging research field among the microwave and antenna technologies is the design of flexible antennas and microwave circuits to be utilized in conformal applications. The combination of those two research topics gives birth to a third one, namely the design of Conformal or Flexible HISs (FHISs), which is the main subject of this dissertation. The problems associated with the FHISs are twofold: characterization and physical realization. The characterization involves the ...

Contributors
Durgun, Ahmet Cemal, Balanis, Constantine A, Aberle, James T, et al.
Created Date
2013

Power management plays a very important role in the current electronics industry. Battery powered and handheld applications require novel power management techniques to extend the battery life. Most systems have multiple voltage regulators to provide power sources to the different circuit blocks and/or sub-systems. Some of these voltage regulators are low dropout regulators (LDOs) which typically require output capacitors in the range of 1's to 10's of µF. The necessity of output capacitors occupies valuable board space and can add additional integrated circuit (IC) pin count. A high IC pin count can restrict LDOs for system-on-chip (SoC) solutions. The presented ...

Contributors
Topp, Matthew, Bakkaloglu, Bertan, Thornton, Trevor, et al.
Created Date
2012

The applications which use MEMS accelerometer have been on rise and many new fields which are using the MEMS devices have been on rise. The industry is trying to reduce the cost of production of these MEMS devices. These devices are manufactured using micromachining and the interface circuitry is manufactured using CMOS and the final product is integrated on to a single chip. Amount spent on testing of the MEMS devices make up a considerable share of the total final cost of the device. In order to save the cost and time spent on testing, researchers have been trying to ...

Contributors
Jangala Naga, Naveen Sai, Ozev, Sule, Bakkaloglu, Bertan, et al.
Created Date
2014

In this thesis, a digital input class D audio amplifier system which has the ability to reject the power supply noise and nonlinearly of the output stage is presented. The main digital class D feed-forward path is using the fully-digital sigma-delta PWM open loop topology. Feedback loop is used to suppress the power supply noise and harmonic distortions. The design is using global foundry 0.18um technology. Based on simulation, the power supply rejection at 200Hz is about -49dB with 81dB dynamic range and -70dB THD+N. The full scale output power can reach as high as 27mW and still keep minimum ...

Contributors
Bai, Jing, Bakkaloglu, Bertan, Arizona State University
Created Date
2015

Three-dimensional (3D) inductors with square, hexagonal and octagonal geometries have been designed and simulated in ANSYS HFSS. The inductors have been designed on Silicon substrate with through-hole via with different width, spacing and thickness. Spice modeling has been done in Agilent ADS and comparison has been made with results of custom excel based calculator and HFSS simulation results. Single ended quality factor was measured as 12.97 and differential ended quality factor was measured as 15.96 at a maximum operational frequency of 3.65GHz. The single ended and differential inductance was measured as 2.98nH and 2.88nH respectively at this frequency. Based on ...

Contributors
Abbey, Hemanshu, Bakkaloglu, Bertan, Kiaei, Sayfe, et al.
Created Date
2012

VCO as a ubiquitous circuit in many systems is highly demanding for the phase noises. Lowering the noise migrated from the power supply has been the trending topics for many years. Considering the Ring Oscillator(RO) based VCO is more sensitive to the supply noise, it is more significant to find out a useful technique to reduce the supply noise. Among the conventional supply noise reduction techniques such as filtering, channel length adjusting for the transistors, and the current noise mutual canceling, the new feature of the 28nm UTBB-FD-SOI process launched by the ST semiconductor offered a new method to reduce ...

Contributors
Tang, Miao, Barnaby, Hugh, Bakkaloglu, Bertan, et al.
Created Date
2018

As residential photovoltaic (PV) systems become more and more common and widespread, their system architectures are being developed to maximize power extraction while keeping the cost of associated electronics to a minimum. An architecture that has become popular in recent years is the "DC optimizer" architecture, wherein one DC-DC converter is connected to the output of each PV module. The DC optimizer architecture has the advantage of performing maximum power-point tracking (MPPT) at the module level, without the high cost of using an inverter on each module (the "microinverter" architecture). This work details the design of a proposed DC optimizer. ...

Contributors
Luster, Daniel, Ayyanar, Raja, Bakkaloglu, Bertan, et al.
Created Date
2014

Efficiency of components is an ever increasing area of importance to portable applications, where a finite battery means finite operating time. Higher efficiency devices need to be designed that don't compromise on the performance that the consumer has come to expect. Class D amplifiers deliver on the goal of increased efficiency, but at the cost of distortion. Class AB amplifiers have low efficiency, but high linearity. By modulating the supply voltage of a Class AB amplifier to make a Class H amplifier, the efficiency can increase while still maintaining the Class AB level of linearity. A 92dB Power Supply Rejection ...

Contributors
Peterson, Cory Jay, Bakkaloglu, Bertan, Barnaby, Hugh, et al.
Created Date
2013

High speed current-steering DACs with high linearity are needed in today's applications such as wired and wireless communications, instrumentation, radar, and other direct digital synthesis (DDS) applications. However, a trade-off exists between the speed and resolution of Nyquist rate current-steering DACs. As the resolution increases, more transistor area is required to meet matching requirements for optimal linearity and thus, the overall speed of the DAC is limited. In this thesis work, a 12-bit current-steering DAC was designed with current sources scaled below the required matching size to decrease the area and increase the overall speed of the DAC. By scaling ...

Contributors
Jankunas, Benjamin, Bakkaloglu, Bertan, Kitchen, Jennifer, et al.
Created Date
2014

Synchronous buck converters have become the obvious choice of design for high efficiency voltage down-conversion applications and find wide scale usage in today's IC industry. The use of digital control in synchronous buck converters is becoming increasingly popular because of its associated advantages over traditional analog counterparts in terms of design flexibility, reduced use of off-chip components, and better programmability to enable advanced controls. They also demonstrate better immunity to noise, enhances tolerance to the process, voltage and temperature (PVT) variations, low chip area and as a result low cost. It enables processing in digital domain requiring a need of ...

Contributors
Kumar, Amit, Bakkaloglu, Bertan, Song, Hongjiang, et al.
Created Date
2013

Optical receivers have many different uses covering simple infrared receivers, high speed fiber optic communication and light based instrumentation. All of them have an optical receiver that converts photons to current followed by a transimpedance amplifier to convert the current to a useful voltage. Different systems create different requirements for each receiver. High speed digital communication require high throughput with enough sensitivity to keep the bit error rate low. Instrumentation receivers have a lower bandwidth, but higher gain and sensitivity requirements. In this thesis an optical receiver for use in instrumentation in presented. It is an entirely monolithic design with ...

Contributors
Lafevre, Kyle, Bakkaloglu, Bertan, Barnaby, Hugh, et al.
Created Date
2011

Digital to analog converters (DACs) find widespread use in communications equipment. Most commercially available DAC's which are intended to be used in transmitter applications come in a dual configuration for carrying the in phase (I) and quadrature (Q) data and feature on chip digital mixing. Digital mixing offers many benefits concerning I and Q matching but has one major drawback; the update rate of the DAC must be higher than the intermediate frequency (IF) which is most commonly a factor of 4. This drawback motivates the need for interpolation so that a low update rate can be used for components ...

Contributors
Nixon, Cliff, Bakkaloglu, Bertan, Arizona State University
Created Date
2013

Modern day deep sub-micron SOC architectures often demand very low supply noise levels. As supply voltage decreases with decreasing deep sub-micron gate length, noise on the power supply starts playing a dominant role in noise-sensitive analog blocks, especially high precision ADC, PLL, and RF SOC's. Most handheld and portable applications and highly sensitive medical instrumentation circuits tend to use low noise regulators as on-chip or on board power supply. Nonlinearities associated with LNA's, mixers and oscillators up-convert low frequency noise with the signal band. Specifically, synthesizer and TCXO phase noise, LNA and mixer noise figure, and adjacent channel power ratios ...

Contributors
Magod Ramakrishna, Raveesh, Bakkaloglu, Bertan, Garrity, Douglas, et al.
Created Date
2014

As integrated technologies are scaling down, there is an increasing trend in the process,voltage and temperature (PVT) variations of highly integrated RF systems. Accounting for these variations during the design phase requires tremendous amount of time for prediction of RF performance and optimizing it accordingly. Thus, there is an increasing gap between the need to relax the RF performance requirements at the design phase for rapid development and the need to provide high performance and low cost RF circuits that function with PVT variations. No matter how care- fully designed, RF integrated circuits (ICs) manufactured with advanced technology nodes necessitate ...

Contributors
Shafiee, Maryam, Ozev, Sule, Diaz, Rodolfo, et al.
Created Date
2018

A 4-phase, quasi-current-mode hysteretic buck converter with digital frequency synchronization, online comparator offset-calibration and digital current sharing control is presented. The switching frequency of the hysteretic converter is digitally synchronized to the input clock reference with less than ±1.5% error in the switching frequency range of 3-9.5MHz. The online offset calibration cancels the input-referred offset of the hysteretic comparator and enables ±1.1% voltage regulation accuracy. Maximum current-sharing error of ±3.6% is achieved by a duty-cycle-calibrated delay line based PWM generator, without affecting the phase synchronization timing sequence. In light load conditions, individual converter phases can be disabled, and the final ...

Contributors
Sun, Ming, Bakkaloglu, Bertan, Garrity, Douglas, et al.
Created Date
2017

During the past decade, different kinds of fancy functions are developed in portable electronic devices. This trend triggers the research of how to enhance battery lifetime to meet the requirement of fast growing demand of power in portable devices. DC-DC converter is the connection configuration between the battery and the functional circuitry. A good design of DC-DC converter will maximize the power efficiency and stabilize the power supply of following stages. As the representative of the DC-DC converter, Buck converter, which is a step down DC-DC converter that the output voltage level is smaller than the input voltage level, is ...

Contributors
Fu, Chao, Bakkaloglu, Bertan, Cao, Yu, et al.
Created Date
2011

Current sensing ability is one of the most desirable features of contemporary current or voltage mode controlled DC-DC converters. Current sensing can be used for over load protection, multi-stage converter load balancing, current-mode control, multi-phase converter current-sharing, load independent control, power efficiency improvement etc. There are handful existing approaches for current sensing such as external resistor sensing, triode mode current mirroring, observer sensing, Hall-Effect sensors, transformers, DC Resistance (DCR) sensing, Gm-C filter sensing etc. However, each method has one or more issues that prevent them from being successfully applied in DC-DC converter, e.g. low accuracy, discontinuous sensing nature, high sensitivity ...

Contributors
Liu, Tao, Bakkaloglu, Bertan, Bakkaloglu, Bertan, et al.
Created Date
2011

Modern Complex electronic system include multiple power domains and drastically varying power consumption patterns, requiring the use of multiple power conversion and regulation units. High frequency switching converters have been gaining prominence in the DC-DC converter market due to their high efficiency. Unfortunately, they are all subject to higher process variations jeopardizing stable operation of the power supply. This research mainly focus on the technique to track changes in the dynamic loop characteristics of the DC-DC converters without disturbing the normal mode of operation using a white noise based excitation and correlation. White noise excitation is generated via pseudo random ...

Contributors
Bakliwal, Priyanka, Ozev, Sule, Bakkaloglu, Bertan, et al.
Created Date
2015

In this work, a 12-bit ADC with three types of calibration is proposed for high speed security applications as well as a precision application. This converter performs for both applications because it satisfies all the necessary specifications such as minimal device mismatch and offset, programmability to decrease aging effects, high SNR for increased ENOB and fast conversion rate. The designed converter implements three types of calibration necessary for offset and gain error, including: a correlated double sampling integrator used in the first stage of the ADC, a power up auto zero technique implemented in the digital code to store any ...

Contributors
Schmelter, Brooke, Bakkaloglu, Bertan, Ogras, Umit, et al.
Created Date
2017

Test cost has become a significant portion of device cost and a bottleneck in high volume manufacturing. Increasing integration density and shrinking feature sizes increased test time/cost and reduce observability. Test engineers have to put a tremendous effort in order to maintain test cost within an acceptable budget. Unfortunately, there is not a single straightforward solution to the problem. Products that are tested have several application domains and distinct customer profiles. Some products are required to operate for long periods of time while others are required to be low cost and optimized for low cost. Multitude of constraints and goals ...

Contributors
Yilmaz, Ender, Ozev, Sule, Bakkaloglu, Bertan, et al.
Created Date
2012

Today's mobile devices have to support computation-intensive multimedia applications with a limited energy budget. In this dissertation, we present architecture level and algorithm-level techniques that reduce energy consumption of these devices with minimal impact on system quality. First, we present novel techniques to mitigate the effects of SRAM memory failures in JPEG2000 implementations operating in scaled voltages. We investigate error control coding schemes and propose an unequal error protection scheme tailored for JPEG2000 that reduces overhead without affecting the performance. Furthermore, we propose algorithm-specific techniques for error compensation that exploit the fact that in JPEG2000 the discrete wavelet transform outputs ...

Contributors
Emre, Yunus, Chakrabarti, Chaitali, Bakkaloglu, Bertan, et al.
Created Date
2012

The high cut-off frequency of deep sub-micron CMOS technologies has enabled the integration of radio frequency (RF) transceivers with digital circuits. However, the challenging point is the integration of RF power amplifiers, mainly due to the low breakdown voltage of CMOS transistors. Silicon-on-insulator (SOI) metal semiconductor field effect transistors (MESFETs) have been introduced to remedy the limited headroom concern in CMOS technologies. The MESFETs presented in this thesis have been fabricated on different SOI-CMOS processes without making any change to the standard fabrication steps and offer 2-30 times higher breakdown voltage than the MOSFETs on the same process. This thesis ...

Contributors
Ghajar, Mohammad Reza, Thornton, Trevor, Aberle, James, et al.
Created Date
2012

Distributed estimation uses many inexpensive sensors to compose an accurate estimate of a given parameter. It is frequently implemented using wireless sensor networks. There have been several studies on optimizing power allocation in wireless sensor networks used for distributed estimation, the vast majority of which assume linear radio-frequency amplifiers. Linear amplifiers are inherently inefficient, so in this dissertation nonlinear amplifiers are examined to gain efficiency while operating distributed sensor networks. This research presents a method to boost efficiency by operating the amplifiers in the nonlinear region of operation. Operating amplifiers nonlinearly presents new challenges. First, nonlinear amplifier characteristics change across ...

Contributors
Santucci, Robert W., Spanias, Andreas, Tepedelenlioðlu, Cihan, et al.
Created Date
2013

The partially-depleted (PD) silicon Metal Semiconductor Field Effect Transistor (MESFET) is becoming more and more attractive for analog and RF applications due to its high breakdown voltage. Compared to conventional CMOS high voltage transistors, the silicon MESFET can be fabricated in commercial standard Silicon-on-Insulator (SOI) CMOS foundries without any change to the process. The transition frequency of the device is demonstrated to be 45GHz, which makes the MESFET suitable for applications in high power RF power amplifier designs. Also, high breakdown voltage and low turn-on resistance make it the ideal choice for switches in the switching regulator designs. One of ...

Contributors
Chen, Bo, Thornton, Trevor, Bakkaloglu, Bertan, et al.
Created Date
2013

Switch mode DC/DC converters are suited for battery powered applications, due to their high efficiency, which help in conserving the battery lifetime. Fixed Frequency PWM based converters, which are generally used for these applications offer good voltage regulation, low ripple and excellent efficiency at high load currents. However at light load currents, fixed frequency PWM converters suffer from poor efficiencies The PFM control offers higher efficiency at light loads at the cost of a higher ripple. The PWM has a poor efficiency at light loads but good voltage ripple characteristics, due to a high switching frequency. To get the best ...

Contributors
Vivek, Parasuram, Bakkaloglu, Bertan, Ogras, Umit, et al.
Created Date
2014

ABSTRACT To meet stringent market demands, manufacturers must produce Radio Frequency (RF) transceivers that provide wireless communication between electronic components used in consumer products at extremely low cost. Semiconductor manufacturers are in a steady race to increase integration levels through advanced system-on-chip (SoC) technology. The testing costs of these devices tend to increase with higher integration levels. As the integration levels increase and the devices get faster, the need for high-calibre low cost test equipment become highly dominant. However testing the overall system becomes harder and more expensive. Traditionally, the transceiver system is tested in two steps utilizing high-calibre RF ...

Contributors
Sreenivassan, Aiswariya, Ozev, Sule, Kiaei, Sayfe, et al.
Created Date
2011