Matching Items (7)
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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
Alternative energy technologies must become more cost effective to achieve grid parity with fossil fuels. Dye sensitized solar cells (DSSCs) are an innovative third generation photovoltaic technology, which is demonstrating tremendous potential to become a revolutionary technology due to recent breakthroughs in cost of fabrication. The study here focused on quality improvement measures undertaken to improve fabrication of DSSCs and enhance process efficiency and effectiveness. Several quality improvement methods were implemented to optimize the seven step individual DSSC fabrication processes. Lean Manufacturing's 5S method successfully increased efficiency in all of the processes. Six Sigma's DMAIC methodology was used to identify and eliminate each of the root causes of defects in the critical titanium dioxide deposition process. These optimizations resulted with the following significant improvements in the production process: 1. fabrication time of the DSSCs was reduced by 54 %; 2. fabrication procedures were improved to the extent that all critical defects in the process were eliminated; 3. the quantity of functioning DSSCs fabricated was increased from 17 % to 90 %.
ContributorsFauss, Brian (Author) / Munukutla, Lakshmi V. (Thesis advisor) / Polesky, Gerald (Committee member) / Madakannan, Arunachalanadar (Committee member) / Arizona State University (Publisher)
Created2012
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
The purpose of this paper is to present a case study on the application of the Lean Six Sigma (LSS) quality improvement methodology and tools to study the analysis and improvement of facilities management (FM) services at a healthcare organization. Research literature was reviewed concerning whether or not LSS has been applied in healthcare-based FM, but no such studies have been published. This paper aims to address the lack of an applicable methodology for LSS intervention within the context of healthcare-based FM. The Define, Measure, Analyze, Improve, and Control (DMAIC) framework was followed to test the hypothesis that LSS can improve the service provided by an FM department responsible for the maintenance and repair of furniture and finishes at a large healthcare organization in the southwest United States of America. Quality improvement curricula and resources offered by the case study organization equipped the FM department to apply LSS over the course of a five-month period. Qualitative data were gathered from pre- and post-intervention surveys while quantitative data were gathered with the Organization’s computerized maintenance management system (CMMS) software. Overall, LSS application proved to be useful for the intended purpose. The author proposes that application of LSS by other FM departments to improve their services could also be successful, which is noteworthy and deserving of continued research.
ContributorsShirey, William T (Author) / Sullivan, Kenneth (Thesis advisor) / Smithwick, Jake (Committee member) / Lines, Brian (Committee member) / Arizona State University (Publisher)
Created2017
Description
With increasing interest in sustainability and green building, organizations are implementing programs such as Leadership in Energy and Environmental Design for Existing Buildings: Operations and Maintenance (LEED-EB) in order to focus corporate sustainability goals on the operations of a facility and the practices of the building occupants. Green building programs help reduce the impact of a facility and bring about several environmental benefits including but not limited to energy conservation, water conservation and material conservation. In addition to various environmental benefits, green building programs can help companies become more efficient. The problem is that organizations are not always successful in their pursuits to achieve sustainability goals. It frequently take years to implement a program, and in many cases the goals for sustainability never come to fruition, when in the mean time resources are wasted, money is spent needlessly and opportunities are lost forever. This thesis addresses how the Six Sigma methodologies used by so many to implement change in their organizations could be applied to the LEED-EB program to help companies achieve sustainability results. A qualitative analysis of the Six Sigma methodologies was performed to determine if and how a LEED-EB program might utilize such methods. The two programs were found to be compatible and several areas for improvements to implementing a LEED-EB program were identified.
ContributorsFurphy, Kimberly (Author) / Hild, Nicholas (Thesis advisor) / Olson, Larry (Committee member) / Sullivan, Kenneth (Committee member) / Arizona State University (Publisher)
Created2010
Description
The purpose of this thesis was to solve a complex problem in the manufacturing industry. The complex problem is the disposition and redeployment of specialized manufacturing equipment while accounting for import, export and supply chain security. The problem-solving approach is discussed in detail, focusing on lean and six sigma methodologies for a solution meeting both company internal and external requirements. This combination of lean and six sigma methodology has been validated by use in a pharmaceutical company. The process flow to dispose equipment properly is presented in detail. The process details can be used as best practices by any company dealing with specialized manufacturing equipment, enabling them to develop a robust process tailored to their organizational structure, hierarchy and resource availability.
ContributorsLedermann, Jean-Pierre (Author) / Danielson, Scott (Thesis advisor) / Biekert, Russell (Committee member) / Lewis, Sharon (Committee member) / Arizona State University (Publisher)
Created2010