A fully on-chip three-terminal switched-capacitor DC-DC converter for low-voltage CMOS LSIs

Abstract

In this paper, we present a fully on-chip switched-capacitor DC-DC converter for low-voltage CMOS LSIs. The converter has three terminals of input, ground, and output, by developing control circuits with fully on-chip configuration. We employ an ultra low-power nanoampere bias current and voltage reference circuit to achieve ultra low-power dissipation of control circuits. It enables us to realize a highly efficient power conversion circuit at light-load-current applications. The converter achieves highly efficient and robust voltage conversion using a pulse frequency modulation control circuit and a start-up/fail-safe circuit. Measurement results demonstrated that the converter can convert a 3.0 V input into 1.2V output successfully. The start-up and fail-safe operations were confirmed through the measurement. The efficiency was more than 50% in the range of 2-6 μA load current.