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- Genre: Masters Thesis
- Creators: Arizona State University
- Creators: Chakraborty, Bijeta
- Creators: Peterson, Cory
- 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
Emergency Medical Services (EMS) first response personnel treat urgent and immediate
illnesses and injuries in prehospital settings, and transport patients to definitive care if needed. EMS originated during warfare. The practice of rescuing wounded soldiers started during the Byzantine Empire, and developed along with other medical advances to the present day. Civilian EMS in the United States grew rapidly starting in the 1960s. Following the landmark National Research Council white paper of “Accidental Death and Disability: The Neglected Disease of Modern Society”, the nation addressed the key issues and problems faced in delivering emergency medical services. Today, colleges and universities often sponsor EMS organizations to serve populations concentrated in complex campuses. These are collectively known as Collegiate-Based Emergency Medical Services (CBEMS). By September 2018, there were 252 registered CBEMS organizations in the United States. Most are affiliated with the National Collegiate Emergency Medical Services Foundation (NCEMSF), which advocates, encourages, and provides support for CBEMS organizations. A survey repeating prior work (1996 and 2005) was sent to all NCEMSF registered CBEMS organizations, and 24 responded. The survey included questions on demographics, response capacities, coverage, organization, and logistics information. Locally, Arizona State University Student Emergency Medical Services (SEMS at ASU) began as an all-student-run volunteer organization in 2008. In 2018, SEMS at ASU became ASU EMS, as an official subdivision of the ASU Environmental Health Safety (EH&S) Department. This study summarizes the history of EMS, investigates the current status of CBEMS organizations and traces the history of ASU EMS from a volunteer group to an official department.
illnesses and injuries in prehospital settings, and transport patients to definitive care if needed. EMS originated during warfare. The practice of rescuing wounded soldiers started during the Byzantine Empire, and developed along with other medical advances to the present day. Civilian EMS in the United States grew rapidly starting in the 1960s. Following the landmark National Research Council white paper of “Accidental Death and Disability: The Neglected Disease of Modern Society”, the nation addressed the key issues and problems faced in delivering emergency medical services. Today, colleges and universities often sponsor EMS organizations to serve populations concentrated in complex campuses. These are collectively known as Collegiate-Based Emergency Medical Services (CBEMS). By September 2018, there were 252 registered CBEMS organizations in the United States. Most are affiliated with the National Collegiate Emergency Medical Services Foundation (NCEMSF), which advocates, encourages, and provides support for CBEMS organizations. A survey repeating prior work (1996 and 2005) was sent to all NCEMSF registered CBEMS organizations, and 24 responded. The survey included questions on demographics, response capacities, coverage, organization, and logistics information. Locally, Arizona State University Student Emergency Medical Services (SEMS at ASU) began as an all-student-run volunteer organization in 2008. In 2018, SEMS at ASU became ASU EMS, as an official subdivision of the ASU Environmental Health Safety (EH&S) Department. This study summarizes the history of EMS, investigates the current status of CBEMS organizations and traces the history of ASU EMS from a volunteer group to an official department.
ContributorsWang, Jada (Author) / Chew, Matt (Thesis advisor) / Maienschein, Jane (Thesis advisor) / Ellison, Karin (Committee member) / Essary, Alison (Committee member) / Arizona State University (Publisher)
Created2019
Description
Hospital Emergency Departments (EDs) are frequently crowded. The Center for
Medicare and Medicaid Services (CMS) collects performance measurements from EDs
such as that of the door to clinician time. The door to clinician time is the time at which a
patient is first seen by a clinician. Current methods for documenting the door to clinician
time are in written form and may contain inaccuracies. The goal of this thesis is to
provide a method for automatic and accurate retrieval and documentation of the door to
clinician time. To automatically collect door to clinician times, single board computers
were installed in patient rooms that logged the time whenever they saw a specific
Bluetooth emission from a device that the clinician carried. The Bluetooth signal is used
to calculate the distance of the clinician from the single board computer. The logged time
and distance calculation is then sent to the server where it is determined if the clinician
was in the room seeing the patient at the time logged. The times automatically collected
were compared with the handwritten times recorded by clinicians and have shown that
they are justifiably accurate to the minute.
Medicare and Medicaid Services (CMS) collects performance measurements from EDs
such as that of the door to clinician time. The door to clinician time is the time at which a
patient is first seen by a clinician. Current methods for documenting the door to clinician
time are in written form and may contain inaccuracies. The goal of this thesis is to
provide a method for automatic and accurate retrieval and documentation of the door to
clinician time. To automatically collect door to clinician times, single board computers
were installed in patient rooms that logged the time whenever they saw a specific
Bluetooth emission from a device that the clinician carried. The Bluetooth signal is used
to calculate the distance of the clinician from the single board computer. The logged time
and distance calculation is then sent to the server where it is determined if the clinician
was in the room seeing the patient at the time logged. The times automatically collected
were compared with the handwritten times recorded by clinicians and have shown that
they are justifiably accurate to the minute.
ContributorsFrisby, Joshua (Author) / Nelson, Brian C (Thesis advisor) / Patel, Vimla L. (Thesis advisor) / Smith, Vernon (Committee member) / Kaufman, David R. (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
The opioid crisis has become one of the most persistent public health crises in America, killing over 100 people a day. The opioid crisis emerged in the late 1990s and 2000s when opioid overdoses began to dramatically increase due to prescription painkillers. Heroin subsequently became a popular drug that was obtained through illicit markets in 2010. More recently, fentanyl, a potent and illicitly manufactured synthetic opioid, has driven a notable increase in the number of opioid overdose deaths. The opioid crisis has impacted many communities across the country. However, some communities are more susceptible to higher rates of opioid use. In order to determine which neighborhoods in Tempe, Arizona are more vulnerable to opioid use the author uses Tempe Emergency Medical Services (EMS) calls for service data and American Community Survey data to address two research questions: 1) What sociodemographic factors at the census-tract level are associated with calls for service to opioid related incidents and 2) are aspects of the physical environment associated with calls for service to opioid related incidents (e.g. vacant units, lack of complete plumbing, multiple unit housing structures)? Understanding community-level risk and protective-factors is essential for furthering the discussion on interventions that aim to address problematic opioid use in vulnerable communities. The current study finds that communities that are economically disadvantaged, and have a higher percentage of units that are vacant have more EMS calls for service to opioid related incidents. However, counter to the proposed hypothesis of social disorganization theory, residential instability was associated with fewer calls for service to opioid related incidents (i.e. higher levels of residential transience). Additionally, racially and ethnically diverse communities had fewer calls for service to opioid related incidents albeit statistically non-significant. These findings have implications for future research and for possible policy implications directed at reducing opioid overdoses.
ContributorsWatts, Seth (Author) / White, Michael D (Thesis advisor) / Chamberlain, Alyssa W (Committee member) / Telep, Cody W (Committee member) / Arizona State University (Publisher)
Created2021