| Summary: | 碩士 === 國立交通大學 === 電機工程學系 === 106 === With the popularity of ultra-high-speed Internet, the concept of Internet of things (IoT) has become a trend of development for future technology. Therefore, more and more Internet of Things portable devices and sensing applications are indispensable to human beings’ life. For the purpose of the energy saving of these products and prolonging the usage time of the internal batteries, DC-DC step-down converters are adopted to achieve the energy transfer between the energy supply and the low power integrated circuit for IoT applications. The conventional two-level DC-DC buck converters must introduce high voltage Power MOSFETs considering needs of the advanced process, which increases the cost. On the contrast, the three-level DC-DC buck converters have the advantages of lower output ripple, lower inductor current ripple and halving the gate driving voltages, which produces smaller output voltage ripple, lowers the current boundary from CCM to DCM with less restriction to the cost and process. However, the flying capacitor unbalancing problems and gate driving issues happen due to the process variation or parasitic effect. In this thesis, an analysis of pointed out flying capacitor unbalancing issue is discussed and a three-level buck converter with effective flying capacitor adaptive balancing (FCAB) technique is proposed. Moreover, an improvement is made to guarantee the normal operation of switches with the switching guarantee circuit. In a word, with the FCAB technique, the proposed three-level buck is more robust without degeneration to two-level one in a wide load range from 30mA to 200mA.
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