Design and Analysis of Adaptive On time Buck and Boost Converters for low voltage applications

Abstract

This thesis gives an extensive analysis of DC - DC switching regulators, designed to newlineprovide an output voltage in the range of 0.8 - 1V. The work presented in this thesis, begins with the implementation of switching Buck converters. To understand and evaluate their performance at low voltages, 5 different kinds of Buck converters have been implemented. These are Adaptive On-time (AOT) voltage-controlled and current-controlled Switched-Inductor (SI) converters, 3 - level AOT SI converter, Hysteretic Switched-Capacitor (SC) converter and AOT Voltage-controlled Hybrid converter. Power efficiency,Output ripple and Response/Settling time are the parameters on which their performance was evaluated. A comparison with the corresponding recent works shows an improvement in the performance. Further, a comparison amongst the implemented buck converters shows that the AOT SI current-controlled converter has the highest power efficiency while the SC converter has the least efficiency but has the advantage of being fully integrable on an IC. The hybrid converter has a low inductor current ripple and reduced inductor losses. newlineIn continuation, the thesis then focuses on AOT Boost converter. Having carried newlineout extensive research on buck converters using different feedback and switch control techniques, a similar analysis for boost converters would be redundant with the results showing a similar trend. Therefore, a different approach was used for the analysis of boost converter. An AOT boost converter was implemented in two different ways. The first is the conventional SPICE circuit implementation of the converter. The second implementation which is the highlight of the research work, is a novel technique used to develop a semi-custom design for the boost converter, by modelling it using Verilog - A. Mixed mode of modelling which is a combination of behavioral and mathematical modelling, has been used. Results of modelling simulation match that of circuit simulation which proves that semi-custom design is as effective as full-custo