Fully Integrated Wide Input Voltage Range Capacitive DC-DC Converters: The Folding Dickson Converter

摘要

This paper presents a modified Dickson converterto achieve wide input range capacitive DC-DC converters.Several implementations are carefully studied and compared,which shows that the folding Dickson converter is the bestchoice, not only for its reduced dynamic losses, but also forits very regular structure and operation. Folding is achievedby merging the terminals of two or more flying capacitors,creating one equivalent flying capacitor. In this design, a fourstage folding Dickson converter is implemented to achieve fourdifferent voltage conversion ratios. A Bootstrapped Gate BoostConverter (BGBC) is proposed which uses a bootstrappingtechnique to generate a floating rail for the flying switches,whose terminal voltages vary by large amounts depending oninput voltage and VCR. The inherent operation of the Dicksontopology is used by copying the voltage of the flying capacitorson a grounded capacitor in one phase, which can then be usedto generate a floating 1.2V in the second phase. The converterhas been implemented in a 90nm technology, achieving amaximum output power of 50mW, peak efficiency of 76.6%in the 2:1 conversion mode, and an average efficiency above60% over the entire Vin and Pout range.