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Project

Fully-Integrated Wide Input Range and Two-Quadrant Switched-Capacitor DC-DC Converters

This work focuses on two specific applications of fully-integrated switched-capacitor DC-DC converters, namely wide range operation and two-quadrant operation. For switched-capacitor DC-DC converters to operate efficiently over a wide input or output voltage range, multiple Voltage Conversion Ratios (VCRs) are required, to counteract the losses associated to its output impedance. To achieve wide range operation, this work proposes to use the Dickson topology as its foundation, transforming it into a wide range topology called the folding Dickson topology. Here, multiple VCRs are achieved through changing the phases of the switches. This operation lumps two or more flying capacitors into a single flying capacitor, which allows the emulation of new VCRs. Furthermore, a small modification to the output stage increases the amount of VCRs even more. These findings were validated through silicon measurements, and boasted an average efficiency of 71% over an input voltage range from 2.5V up to 8V, which is more than 4.5 times the technologies supply voltage. The regularity of this topology allows it to be extended to achieve even higher voltage ranges, at a minimal design overhead.

Two-quadrant DC-DC converters on the other hand might alleviate issues that are encountered with getting the ever increasing currents on-chip. In stead of supplying loads in parallel, they are put in stacked voltage domains. The shared node now needs to be balanced by a DC-DC converter, capable of both sourcing and sinking current. Switched-capacitor DC-DC converters require two VCRs to achieve both modes of operation. This work presented the first fully-integrated two-quadrant switched-capacitor DC-DC converter, capable of supplying loads in stacked voltage domains with variable load voltages (0.75-1.1V), while very high systems efficiencies up to 99.6% are achievable thanks to the low-power two-fold control loop.

Date:3 Dec 2012 →  13 Dec 2017
Keywords:switched-capacitor, DC-DC converter, fully-integrated, wide range, two-quadrant, folding Dickson
Disciplines:Nanotechnology, Design theories and methods
Project type:PhD project