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- Genre: Masters Thesis
- Creators: Arizona State University
- Creators: Chakraborty, Bijeta
- Member of: ASU Electronic Theses and Dissertations
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
Class D Amplifiers are widely used in portable systems such as mobile phones to achieve high efficiency. The demands of portable electronics for low power consumption to extend battery life and reduce heat dissipation mandate efficient, high-performance audio amplifiers. The high efficiency of Class D amplifiers (CDAs) makes them particularly attractive for portable applications. The Digital class D amplifier is an interesting solution to increase the efficiency of embedded systems. However, this solution is not good enough in terms of PWM stage linearity and power supply rejection. An efficient control is needed to correct the error sources in order to get a high fidelity sound quality in the whole audio range of frequencies. A fundamental analysis on various error sources due to non idealities in the power stage have been discussed here with key focus on Power supply perturbations driving the Power stage of a Class D Audio Amplifier. Two types of closed loop Digital Class D architecture for PSRR improvement have been proposed and modeled. Double sided uniform sampling modulation has been used. One of the architecture uses feedback around the power stage and the second architecture uses feedback into digital domain. Simulation & experimental results confirm that the closed loop PSRR & PS-IMD improve by around 30-40 dB and 25 dB respectively.
ContributorsChakraborty, Bijeta (Author) / Bakkaloglu, Bertan (Thesis advisor) / Garrity, Douglas (Committee member) / Ozev, Sule (Committee member) / Arizona State University (Publisher)
Created2012
Description
In today's era a lot of the construction projects suffer from time delay, cost overrun and quality defect. Incentive provisions are found to be a contracting strategy to address this potential problem. During last decade incentive mechanisms have gained importance, and they are starting to become adopted in the construction projects. Most of the previous research done in this area was purely qualitative, with a few quantitative studies. This study aims to quantify the performance of incentives in construction by collecting the data from more than 30 projects in United States through a questionnaire survey. First, literature review addresses the previous research work related to incentive types, incentives in construction industry, incentives in other industry and benefits of incentives. Second, the collected data is analyzed with statistical methods to test the significance of observed changes between two data sets i.e. incentive projects and non-incentive projects. Finally, the analysis results provide evidence for the significant impact of having incentives; reduced the cost and schedule growth in construction projects in United States.
ContributorsPaladugu, Bala Sai Krishna (Author) / El Asmar, Mounir (Thesis advisor) / Ernzen, James (Committee member) / Sullivan, Kenneth (Committee member) / Arizona State University (Publisher)
Created2015
Description
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 -68dB THD+N. The system efficiency at full scale is about 82%.
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 -68dB THD+N. The system efficiency at full scale is about 82%.
ContributorsBai, Jing (Author) / Bakkaloglu, Bertan (Thesis advisor) / Arizona State University (Publisher)
Created2015
Description
This thesis presents a literature research analyzing the cost overrun of the construction industry worldwide, exploring documented causes for cost overrun, and documented parties responsible for the inefficiency. The analysis looks at a comparison between the metrics of construction projects in different continents and regions. Multiple publication databases were used to look into over 300 papers. It is shown that although construction demands are increasing, cost overrun on these projects is not decreasing at the same rate around the world. This thesis also presents a possible solution to improve cost overrun in the construction industry, through the use of the Best Value Performance Information Procurement System (BV PIPS). This is a system that has been utilized in various countries around the world, and has documented evidence that it may be able to alleviate the overrun occurring in the construction industry.
ContributorsGoyal, Abhinav (Author) / Kashiwagi, Jacob (Thesis advisor) / Kashiwagi, Dean (Committee member) / Chong, Oswald (Committee member) / Arizona State University (Publisher)
Created2017
Description
In this era of high-tech computer advancements and tremendous programmable computer capabilities, construction cost estimation still remains a knowledge-intensive and experience driven task. High reliance on human expertise, and less accuracy in the decision support tools render cost estimation error prone. Arriving at accurate cost estimates is of paramount importance because it forms the basis of most of the financial, design, and executive decisions concerning the project at subsequent stages. As its unique contribution to the body of knowledge, this paper analyzes the deviations and behavior of costs associated with different construction activities involved in commercial office tenant improvement (TI) projects. The aim of this study is to obtain useful micro-level cost information of various construction activities that make up for the total construction cost of projects. Standardization and classification of construction activities have been carried out based on Construction Specifications Institute’s (CSI) MasterFormat® division items. Construction costs from 51 office TI projects completed during 2015 and 2016 are analyzed statistically to understand the trends among various construction activities involved. It was found that the interior finishes activities showed a much higher cost of construction, and a comparatively higher variation than the mechanical, electrical, and plumbing (MEP) trades. The statistical analysis also revealed a huge scope of energy saving measures that could be achieved in such TI projects because of the absence of energy management systems (EMS) found in 66% of the projects.
ContributorsGhosh, Arunabho (Author) / Grau, David (Thesis advisor) / Ayer, Steven (Committee member) / Parrish, Kristen (Committee member) / Arizona State University (Publisher)
Created2016
Description
This thesis draws on industry experience and academic literature to highlight several problems facing the construction and facility management industries. These problems include issues with product delivery performance and financial failures that often lead firms to spend much more than anticipated, while obtaining much less of a product. Transaction-cost economics theory and literature are presented as a model for understanding, predicting, and preventing these problems. Transaction-cost economics suggests that specificity and uncertainty, two key characteristics of industry transactions, are improperly aligned with governance structures, leading to preventable failures. This thesis highlights several case studies in which these failures occur and argues that the correct application of this theory can mitigate many of these problems. A final case study illustrates how this alignment can make a difference in outcome without a compromise of quality.
ContributorsRice, Michael L., M.S (Author) / Sullivan, Kenneth (Thesis advisor) / Stone, Brian (Committee member) / Smithwick, Jake (Committee member) / Arizona State University (Publisher)
Created2019