A Current-mode, Boost DC/DC Converter for Small Inductances

Inhalt:
This paper presents a CMOS circuit for the on-chip generation of a high voltage using an optimized design of a step-up DC/DC converter with inductor values in the <1 microH range. The work had the objective to replace commonly used charge-pumps with an inductor-based solution of higher power efficiency. The physical dimensions of the inductor were limited to be suitable for integration into low-height, standard IC-packages (e.g. BGAs). The described DC/DC converter is based on a current-mode, oscillator-stabilized boost architecture. The circuit generates an output voltage of 6V from an 1.8V input source and achieves a simulated efficiency of 60% for a 12mA current load with an 150nH inductor. The active die size without pads is 0.5mm2 in a 0.25micrometer CMOS process.