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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 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
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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

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
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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

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

In the end, an increase in repurchases of company stock will also influence the rate of dividends to increase. This means, an investor should not necessarily worry about the dividends they receive, but rather to see if the company is making profit at a consistent rate and reinvesting into value-added

In the end, an increase in repurchases of company stock will also influence the rate of dividends to increase. This means, an investor should not necessarily worry about the dividends they receive, but rather to see if the company is making profit at a consistent rate and reinvesting into value-added activities. Through the major pillars of finance, technology, legal, and human resources, the budget for reinvestment can be optimized by investing into these respective categories with percentages that are mindful of the specific companies needs and functions. Any firm that chooses to ensure proven methods of growth will enact a combination of these four verticals. A larger emphasis on finance will branch out efficiency in the entire organization, as finance control everything from the toilet paper to the acquisitions the company is making. The more technology is used to reduce redundancy and inefficient or costly operations, the more capability the organization will have. IT, however, comes with its technical challenges; having a team on-hand or even outsourced, to solve the critical problems to help the business continue operation. Over-reliance into technology can be detrimental to a business as well if clear processes are not set about straight to counteract problems the business will face like IT ticketing systems or recovery and continuity support. Therefore, technology will require a larger chunk of attention as well.

The upcoming legal and HR investments a company will make will depend upon its current position and thus the restructuring will differ for every firm. Each company has its own flavour and style of work. In that regard, the required legal counsel will vary; different problems will require different solutions for risk control and management, which are often professionally advised by intelligent corporate counsel. This ability to hire efficient legal counsel would not arise in the first place if a firm were to give out dividends; the leftover profit would have gone towards the shareholders and not back into growing the equity of the business. Lastly, nothing is possible without the contribution of people, and their efforts. A quality that long-lasting, successful businesses have, is they are investing in their people and development. Paying salaries, insurances, bonuses, all requires extra capital that is needed to be set aside in order to grow human capital. Good people, better people. There are qualities for each role that need to be defined and a process for attracting talent needs to be invested in. This process can also include outsourcing to an external firm who specializes in these strategies. By retaining profits internally, the company is able to stretch its legs to have further reach upon the market they work in. Financially and statistically, dividends are likely to grow as well with the increase in equity due to the increase in security an investor feels with more cash reserve and liquidity within the company.

All in all, a company should not be pressured into giving out periodic payments in predetermined timeframes, in other words a dividend, to investors even when they are insisting. Rather, pitch and prove, a new method for reinvestment within the company that will raise the value of the company, through proven methods like the value chain model, to increase the equity in the company. By expanding the scope and capability, the company is allowing for a larger target market which will reap more benefits; none of it would be possible if it had continued to give out large percentages of capital to investors as dividends. Companies, and investors, should not be worried about dividends at all as a matter of fact; an increase in stock buyback, in other words reinvesting into the company, will increase the rate of dividends anyway, due to increased confidence and capital within the company.

ContributorsKabra, Dev (Author) / Ahern, James (Thesis director) / Kabra , J. (Committee member) / Barrett, The Honors College (Contributor) / Department of Information Systems (Contributor) / School of Politics and Global Studies (Contributor) / Department of Finance (Contributor)
Created2022-05
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ContributorsKabra, Dev (Author) / Ahern, James (Thesis director) / Kabra , J. (Committee member) / Barrett, The Honors College (Contributor) / Department of Information Systems (Contributor)
Created2022-05
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ContributorsKabra, Dev (Author) / Ahern, James (Thesis director) / Kabra , J. (Committee member) / Barrett, The Honors College (Contributor) / Department of Information Systems (Contributor)
Created2022-05
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ContributorsKabra, Dev (Author) / Ahern, James (Thesis director) / Kabra , J. (Committee member) / Barrett, The Honors College (Contributor) / Department of Information Systems (Contributor)
Created2022-05