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- Creators: Arizona State University
- Creators: Barrett, The Honors College
Description
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 preceding the DACs. In this thesis the design of an interpolating DAC integrated circuit (IC) to be used in a transmitter application for generating a 100MHz IF is presented. Many of the transistor level implementations are provided. The tradeoffs in the design are analyzed and various options are discussed. This thesis provides a basic foundation for designing an IC of this nature and will give the reader insight into potential areas of further research. At the time of this writing the chip is in fabrication therefore this document does not contain test results.
ContributorsNixon, Cliff (Author) / Bakkaloglu, Bertan (Thesis advisor) / Arizona State University (Publisher)
Created2013
Description
Research has shown that the ability to smell is the most direct sense an individual can experience. With every breath a person takes, the brain recognizes thousands of molecules and makes connections with our memories to determine their composition. With the amount of research looking into how and why we smell, researchers still have little understanding of how the nose and brain process an aroma, and how emotional and physical behavior is impacted. This research focused on the affects smell has on a caregiver in a simulated Emergency Department setting located in the SimET of Banner Good Samaritan Medical Center in Phoenix, Arizona. The study asked each participant to care for a programmed mannequin, or "patient", while performing simple computer-based tasks, including memory and recall, multi-tasking, and mood-mapping to gauge physical and mental performance. Three different aromatic environments were then introduced through diffusion and indirect inhalation near the participants' task space: 1) a control (no smell), 2) an odor (simulated dirty feet), and 3) an aroma (one of four true essential oils plus a current odor-eliminating compound used in many U.S. Emergency Departments). This study was meant to produce a stressful environment by leading the caregiver to stay in constant movement throughout the study through timed tasks, uncooperative equipment, and a needy "patient". The goal of this research was to determine if smells, and of what form of pleasantness and repulsiveness, can have an effect on the physical and mental performance of emergency caregivers. Findings from this study indicated that the "odor eliminating" method currently used in typical Emergency Departments, coffee grounds, is more problematic than helpful, and the introduction of true essential oils may not only reduce stress, but increase efficiency and, in turn, job satisfaction.
ContributorsClark, Carina M (Author) / Bernardi, Jose (Thesis advisor) / Heywood, William (Committee member) / Watts, Richard (Committee member) / Rosso, Rachel (Committee member) / Arizona State University (Publisher)
Created2013
Description
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 Ratio (PSRR) Class AB amplifier and a Class H amplifier were designed in a 0.24um process for portable audio applications. Using a multiphase buck converter increased the efficiency of the Class H amplifier while still maintaining a fast response time to respond to audio frequencies. The Class H amplifier had an efficiency above the Class AB amplifier by 5-7% from 5-30mW of output power without affecting the total harmonic distortion (THD) at the design specifications. The Class H amplifier design met all design specifications and showed performance comparable to the designed Class AB amplifier across 1kHz-20kHz and 0.01mW-30mW. The Class H design was able to output 30mW into 16Ohms without any increase in THD. This design shows that Class H amplifiers merit more research into their potential for increasing efficiency of audio amplifiers and that even simple designs can give significant increases in efficiency without compromising linearity.
ContributorsPeterson, Cory (Author) / Bakkaloglu, Bertan (Thesis advisor) / Barnaby, Hugh (Committee member) / Kiaei, Sayfe (Committee member) / Arizona State University (Publisher)
Created2013
Description
This thesis describes the design process used in the creation of a two stage cellular power amplifier. A background for understanding amplifier linearity, device properties, and ACLR estimation is provided. An outline of the design goals is given with a focus on linearity with high efficiency. The full design is broken into smaller elements which are discussed in detail. The main contribution of this thesis is the description of a novel interstage matching network topology for increasing efficiency. Ultimately the full amplifier design is simulated and compared to the measured results and design goals. It was concluded that the design was successful, and used in a commercially available product.
ContributorsSpivey, Erin (Author) / Aberle, James T., 1961- (Thesis advisor) / Kitchen, Jennifer (Committee member) / Ozev, Sule (Committee member) / Arizona State University (Publisher)
Created2012
Description
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 of both control modes, both loops are used together with the control switched from one loop to another based on the load current. Such architectures are referred to as hybrid converters. While transition from PFM to PWM loop can be made by estimating the average load current, transition from PFM to PWM requires voltage or peak current sensing. This theses implements a hysteretic PFM solution for a synchronous buck converter with external MOSFET's, to achieve efficiencies of about 80% at light loads. As the PFM loop operates independently of the PWM loop, a transition circuit for automatically transitioning from PFM to PWM is implemented. The transition circuit is implemented digitally without needing any external voltage or current sensing circuit.
ContributorsVivek, Parasuram (Author) / Bakkaloglu, Bertan (Thesis advisor) / Ogras, Umit Y. (Committee member) / Song, Hongjiang (Committee member) / Arizona State University (Publisher)
Created2014
Description
Semiconductor device scaling has kept up with Moore's law for the past decades and they have been scaling by a factor of half every one and half years. Every new generation of device technology opens up new opportunities and challenges and especially so for analog design. High speed and low gain is characteristic of these processes and hence a tradeoff that can enable to get back gain by trading speed is crucial. This thesis proposes a solution that increases the speed of sampling of a circuit by a factor of three while reducing the specifications on analog blocks and keeping the power nearly constant. The techniques are based on the switched capacitor technique called Correlated Level Shifting. A triple channel Cyclic ADC has been implemented, with each channel working at a sampling frequency of 3.33MS/s and a resolution of 14 bits. The specifications are compared with that based on a traditional architecture to show the superiority of the proposed technique.
ContributorsSivakumar, Balasubramanian (Author) / Farahani, Bahar Jalali (Thesis advisor) / Garrity, Douglas (Committee member) / Bakkaloglu, Bertan (Committee member) / Aberle, James T., 1961- (Committee member) / Arizona State University (Publisher)
Created2012
Description
Lean and Green construction methodologies are prevalent in today's construction industry. Green construction implementation in buildings has progressed quickly due to the popularity and development of building rating systems, such as LEED, Green Globes, and the Living Building Challenge. Similarly, lean construction has become more popular as this philosophy often leads to efficient construction and improved owner satisfaction. Green construction is defined as using sustainable materials in the construction process to eliminate environmental degradation and ensure that material and equipment use aligns with the design intent and promotes efficient building performance. Lean construction is defined as a set of operational/systematic processes that reduce waste and eliminates defects in the project process throughout its lifecycle. This paper describes the implementation of Lean and Green construction processes to determine the trends that each methodology contributes to a project as well as how these methodologies synergize. The authors identified common elements of each methodology through semi-structured interviews with several construction industry professionals who had extensive experience with lean and green construction. Interviewees report lean and green construction philosophies are different "flavors" of the industry; however, interviewees also state if implemented together, these processes often result in a high-performance building.
ContributorsMaris, Kelsey Lynn (Co-author) / Parrish, Kristen (Co-author, Thesis director) / Olson, Patricia (Committee member) / Barrett, The Honors College (Contributor) / School of Sustainability (Contributor) / Del E. Webb Construction (Contributor)
Created2015-05
Description
The Performance Based Studies Research Studies Group (PBSRG) at Arizona State University (ASU) has been studying the cause of increased cost and time in construction and other projects for the last 20 years. Through two longitudinal studies with a group of owners in the state of Minnesota (400 tests over six years) and the US Army Medical Command (400 tests over four years), the client/buyer has been identified as the largest risk and source of project cost and time deviations. This has been confirmed by over 1,500 tests conducted over the past 20 years. The focus of this research effort is to analyze the economic and performance impact of a delivery process of construction called the Job Order Contracting (JOC) process, to evaluate the value (in terms of time, cost, and customer satisfaction) achieved when utilizing JOC over other traditional methods to complete projects. JOC's strength is that it minimizes the need for the owner to manage, direct and control (MDC) through a lengthy traditional process of design, bid, and award of a construction contract. The study identifies the potential economic savings of utilizing JOC. This paper looks at the results of an ongoing study surveying eight different public universities. The results of the research show that in comparison to more traditional models, JOC has large cost savings, and is preferable among most owners who have used multiple delivery systems.
ContributorsLi, Hao (Author) / Kashiwagi, Dean (Thesis director) / Kashiwagi, Jacob (Committee member) / Industrial, Systems (Contributor) / Department of Information Systems (Contributor) / Barrett, The Honors College (Contributor)
Created2015-12
Description
The U.S. Navy and other amphibious military organizations utilize a derivation of the traditional side stroke called the Combat Side Stroke, or CSS, and tout it as the most efficient technique available. Citing its low aerobic requirements and slow yet powerful movements as superior to the traditionally-best front crawl (freestyle), the CSS is the go-to stroke for any operation in the water. The purpose of this thesis is to apply principles of Industrial Engineering to a real-world situation not typically approached from a perspective of optimization. I will analyze pre-existing data about various swim strokes in order to compare them in terms of efficiency for different variables. These variables include calories burned, speed, and strokes per unit distance, as well as their interactions. Calories will be measured by heart rate monitors, converting BPM to calories burned. Speed will be measured by stopwatch and observer. Strokes per unit distance will be measured by observer. The strokes to be analyzed include the breast stroke, crawl stroke, butterfly, and combat side stroke. The goal is to informally test the U.S. Navy's claim that the combat side stroke is the optimum stroke to conserve energy while covering distance. Because of limitations in the scope of the project, analysis will be done using data collected from literary sources rather than through experimentation. This thesis will include a design of experiment to test the findings here in practical study. The main method of analysis will be linear programming, followed by hypothesis testing, culminating in a design of experiment for future progress on this topic.
ContributorsGoodsell, Kevin Lewis (Author) / McCarville, Daniel R. (Thesis director) / Kashiwagi, Jacob (Committee member) / Industrial, Systems (Contributor) / Barrett, The Honors College (Contributor)
Created2014-12
Description
This project analyzes the large array of managerial leadership research in congruence with the wide field of workplace communication to attempt to determine the importance of refining communication channels between managers and employees as well as articulate the core competencies a manager should exhibit when practicing exemplary communication in their respective work environment. The preliminary sections of this thesis will establish the currently existing foundations utilized and narrow the wide range of research available to applicable information regarding positive workplace communication, influencing factors in a feedback loop from the employee’s perspective, as well as leadership aspects and actions a manager can alter or initiate to improve their workplace’s environment through communicational refinement. This research is supplemented with a survey that was administered to Arizona State University student leaders who were involved in coordinating the Regional Business Conference on the Polytechnic campus. The survey data is designed to either confirm or contradict the findings of the literature. The objective of this project is to synthesize an overview of a manager’s responsibilities and recommend actions to tailor and improve workplace communication
ContributorsWhelan-Gonzales, Luke Andrew (Author) / Schmitz, Troy (Thesis director) / Pegg, TJ (Committee member) / Historical, Philosophical & Religious Studies (Contributor) / Dean, W.P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05