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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 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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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

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%.
ContributorsBai, Jing (Author) / Bakkaloglu, Bertan (Thesis advisor) / Arizona State University (Publisher)
Created2015
Description

My honors thesis took the form of a creative project. My final deliverables are my research presentation (pdf attachment) and solar powered electric scooter (image attachment). The goal of my project was to fix a second-hand electric scooter and create a solar-powered charger for its battery. The research portion of

My honors thesis took the form of a creative project. My final deliverables are my research presentation (pdf attachment) and solar powered electric scooter (image attachment). The goal of my project was to fix a second-hand electric scooter and create a solar-powered charger for its battery. The research portion of my creative project focused on exploring the circuit elements in a solar charging schematic and their relationships to power output. First, I explored methods of maximizing power output of the basic solar charging schematic. To find the maximum power output based on different settings of photocurrent (sunlight), I wrote a MATLAB code to calculate maximum power based on its derivative with respect to voltage set equal to zero. Finding this maximum power point in MATLAB allowed me to find its corresponding current and voltage output to produce that exact power. With these max current and voltage values, I was able to solve for an ideal resistor value to set in series with the solar panel in order to achieve these values. In doing so, I designed a maximum power point tracker (MPPT). This became an essential component in my charger’s final design. Next, I explored the microcircuit level of a solar panel schematic. In order to do so, I had to break my single diode model into several diodes in series, resulting in the overall solar panel voltage drop (aka the voltage rating of the solar panel) being divided N times. To find what this N value for a given solar panel is, I performed a lab experiment using a small solar panel and a floodlight to gather the panel’s turn on current and open circuit voltage. These two values helped me find the solar panel’s N value after linearizing the lab data. Now, with a much deeper understanding of solar charging circuitry, I was able to move forward with the design and implementation phase. The design and implementation portion of my creative project included the physical assembly of the solar-powered scooter. First, I analyzed the efficiency differences between having an AC coupled vs. DC coupled system. Due to the added complexity of AC conversions, I deemed it unnecessary to use an inverter in the charger. The charging schematic I designed only called for a charge controller and MPPT, both parts that could easily DC couple the system. Keeping the system in DC from solar panel to battery was definitely the most efficient method, so DC coupling was my final selection. Next, I calculated the required current and voltage output of my charger to meet the specs of the battery and the requirements I set for my project. Finally, I designed a solar array based on these ratings. The final design includes one 30 W panel in parallel with two series-connected 5W panels. The two series panels are affixed on the scooter neck for a built in charge design so that the scooter can be charged anywhere (outside while not in use). The big panel can be connected using a parallel branch in the charging cord that I spliced for added current if charging is set up in a stationary setting (by a window at home). The final design serves the need for sustainable micro mobility in a daily 50% depletion use case kept above 20% charged at all times.

ContributorsLevin, Aviva (Author) / Barnaby, Hugh (Thesis director) / Schoepf, Jared (Committee member) / Barrett, The Honors College (Contributor) / Electrical Engineering Program (Contributor)
Created2023-05
ContributorsLevin, Aviva (Author) / Barnaby, Hugh (Thesis director) / Schoepf, Jared (Committee member) / Barrett, The Honors College (Contributor) / Electrical Engineering Program (Contributor)
Created2023-05
Description
My honors thesis took the form of a creative project. My final deliverables are my research presentation (pdf attachment) and solar powered electric scooter (image attachment). The goal of my project was to fix a second-hand electric scooter and create a solar-powered charger for its battery. The research portion of my

My honors thesis took the form of a creative project. My final deliverables are my research presentation (pdf attachment) and solar powered electric scooter (image attachment). The goal of my project was to fix a second-hand electric scooter and create a solar-powered charger for its battery. The research portion of my creative project focused on exploring the circuit elements in a solar charging schematic and their relationships to power output. First, I explored methods of maximizing power output of the basic solar charging schematic. To find the maximum power output based on different settings of photocurrent (sunlight), I wrote a MATLAB code to calculate maximum power based on its derivative with respect to voltage set equal to zero. Finding this maximum power point in MATLAB allowed me to find its corresponding current and voltage output to produce that exact power. With these max current and voltage values, I was able to solve for an ideal resistor value to set in series with the solar panel in order to achieve these values. In doing so, I designed a maximum power point tracker (MPPT). This became an essential component in my charger’s final design. Next, I explored the microcircuit level of a solar panel schematic. In order to do so, I had to break my single diode model into several diodes in series, resulting in the overall solar panel voltage drop (aka the voltage rating of the solar panel) being divided N times. To find what this N value for a given solar panel is, I performed a lab experiment using a small solar panel and a floodlight to gather the panel’s turn on current and open circuit voltage. These two values helped me find the solar panel’s N value after linearizing the lab data. Now, with a much deeper understanding of solar charging circuitry, I was able to move forward with the design and implementation phase. The design and implementation portion of my creative project included the physical assembly of the solar-powered scooter. First, I analyzed the efficiency differences between having an AC coupled vs. DC coupled system. Due to the added complexity of AC conversions, I deemed it unnecessary to use an inverter in the charger. The charging schematic I designed only called for a charge controller and MPPT, both parts that could easily DC couple the system. Keeping the system in DC from solar panel to battery was definitely the most efficient method, so DC coupling was my final selection. Next, I calculated the required current and voltage output of my charger to meet the specs of the battery and the requirements I set for my project. Finally, I designed a solar array based on these ratings. The final design includes one 30 W panel in parallel with two series-connected 5W panels. The two series panels are affixed on the scooter neck for a built in charge design so that the scooter can be charged anywhere (outside while not in use). The big panel can be connected using a parallel branch in the charging cord that I spliced for added current if charging is set up in a stationary setting (by a window at home). The final design serves the need for sustainable micro mobility in a daily 50% depletion use case kept above 20% charged at all times.
ContributorsLevin, Aviva (Author) / Barnaby, Hugh (Thesis director) / Schoepf, Jared (Committee member) / Barrett, The Honors College (Contributor) / Electrical Engineering Program (Contributor)
Created2023-05
ContributorsLevin, Aviva (Author) / Barnaby, Hugh (Thesis director) / Schoepf, Jared (Committee member) / Barrett, The Honors College (Contributor) / Electrical Engineering Program (Contributor)
Created2023-05