20.1 A light-load-efficient 11/1 switched-capacitor DC-DC converter with 94.7% efficiency while delivering 100mW at 3.3V

Getting from the mains to a few volts to power electronic circuits requires a very large voltage conversion ratio since the rectified US and EU mains have DC levels of 169V and 325V, respectively. Primary converters, such as flyback converters, use the winding ratio of the isolation transformer to achieve large step-down ratios and generate bus voltages of about 12V. The higher the bus voltage, the higher the efficiency of the primary converter can be and the lower the bus impedance loss. This motivates the investigation of highly efficient DC-DC converters with high voltage conversion ratios (VCRs) to use as secondary converters in AC-DC applications.