Browsing by Subject "DC-DC converters"
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Item Design of Integrated Voltage-Mode Controlled DC-DC Buck Converter(2013-05) Wang, Longfei; Li, Changzhi; Bayne, Stephen B.This thesis work focuses on the design of integrated voltage-mode controlled synchronous buck converter to achieve high efficiency. Concept of DC-DC converters are discussed first and synchronous rectification techniques are used for the design. This design work can be used for single lithium-ion battery operated portable electronic system. The input voltage range of the converter is 3.5V-5V and the maximum load current can be as high as 950mA. A high switching frequency of 1MHz is used for the design to achieve smaller inductor and capacitor value as well as lower voltage ripple. The functional blocks of this designed synchronous buck converter include power stage circuit, compensated error amplifier, PWM comparator, dead time generation circuit and gate driver. Based on AMI0.5 um process, the whole circuit system as well as each functional block are simulated and the simulation results show that the output voltage ripple of this synchronous buck converter is smaller than 10mV. At 6Ω load resistance, the synchronous buck converter has efficiency greater than 96% and at input voltage of 3.7V, the synchronous buck converter has efficiency greater than 90%.Item Fully integrated CMOS charge pump design(2010-08) Anumula, Sarat Reddy; Hassibi, Arjang; McDermott, MarkDue to the continuous power supply reduction, Charge Pumps, also referred to as DC-DC converters, circuits are widely used in integrated circuits (ICs) to generate high voltages for many applications, such as EEP-ROMs, Flash memories for programming and erasing of the floating gate, switched capacitor circuits, operational amplifiers, voltage regulators, LCD drivers, piezoelectricactuators, etc. A charge pump is a kind of DC to DC converter that uses capacitors as energy storage elements to create either a higher or lower voltage power source. The development of the charge pumps is motivated by ever increasing the needs for the small form factor (i.e small size and low weight), high-conversion-efficiency and low costpower management system, which is the best candidate suitable to meet the needs of continuosly shrinking portable electronic devices like MP3 players, cellular phones, PDA's.Item High Gain Transformerless DC-DC Converters for Renewable Energy Sources(2011-08-08) Denniston, Nicholas AaronRenewable energy sources including photovoltaic cells, fuel cells, and wind turbines require converters with high voltage gain in order to interface with power transmission and distribution networks. These conversions are conventionally made using bulky, complex, and costly transformers. Multiple modules of single-switch, single-inductor DC-DC converters can serve these high-gain applications while eliminating the transformer. This work generally classifies multiple modules of single-switch, single-inductor converters as high gain DC-DC converters transformers. The gain and efficiency of both series and cascade configurations are investigated analytically, and a method is introduced to determine the maximum achievable gain at a given efficiency. Simulations are used to verify the modeling approach and predict the performance at different power levels. Experimental prototypes for both low power and high power applications demonstrate the value of multiple module converters in high gain DC-DC converters for renewable energy applications.Item Low Power DC-DC Converters and a Low Quiescent Power High PSRR Class-D Audio Amplifier(2013-12-03) Torres, JoselynHigh-performance DC-DC voltage converters and high-efficient class-D audio amplifiers are required to extend battery life and reduce cost in portable electronics. This dissertation focuses on new system architectures and design techniques to reduce area and minimize quiescent power while achieving high performance. Experimental results from prototype circuits to verify theory are shown. Firstly, basics on low drop-out (LDO) voltage regulators are provided. Demand for system-on-chip solutions has increased the interest in LDO voltage regulators that do not require a bulky off-chip capacitor to achieve stability, also called capacitor- less LDO (CL-LDO) regulators. Several architectures have been proposed; however, comparing these reported architectures proves difficult, as each has a distinct process technology and specifications. This dissertation compares CL-LDOs in a unified manner. Five CL-LDO regulator topologies were designed, fabricated, and tested under common design conditions. Secondly, fundamentals on DC-DC buck converters are presented and area reduction techniques for the external output filter, power stage, and compensator are proposed. A fully integrated buck converter using standard CMOS technology is presented. The external output filter has been fully-integrated by increasing the switching frequency up to 45 MHz. Moreover, a monolithic single-input dual-output buck converter is proposed. This architecture implements only three switches instead of the four switches used in conventional solutions, thus potentially reducing area in the power stage through proper design of the power switches. Lastly, a monolithic PWM voltage mode buck converter with compact Type-III compensation is proposed. This compensation scheme employs a combination of Gm-RC and Active-RC techniques to reduce the area of the compensator, while maintaining low quiescent power consumption and fast transient response. The proposed compensator reduces area by more than 45% when compared to an equivalent conventional Type-III compensator. Finally, basics on class-D audio amplifiers are presented and a clock-free current controlled class-D audio amplifier using integral sliding mode control is proposed. The proposed amplifier achieves up to 82 dB of power supply rejection ratio and a total harmonic distortion plus noise as low as 0.02%. The IC prototype?s controller consumes 30% less power than those featured in recently published works.