ScholarWorks@경상국립대학교

초록

This paper introduces a low-power voltage regulator designed to significantly reduce the cold-start time in energy-harvesting (EH) systems powered by piezo-electric harvesters (PEH) and triboelectric nanogenerators (TENG). These harvesters are characterized by high voltage and limited current outputs. Traditional EH systems bypass the energy charger during cold-start, requiring the battery to accumulate a large charge and causing the harvester to operate below its maximum-power point (MPP), resulting in a lengthy start-up delay. The proposed regulator directly utilizes the rectified DC output from the harvesters to immediately generate the required supply voltage. It features a digitally controlled loop with a constant-energy-per-cycle ring-oscillator (CERO) based comparator that adjusts the switching frequency based on the error between the target and sensed output voltage. This approach minimizes quiescent current to under 1 & micro;A by further reducing speed at the target voltage. Fabricated using a 180 nm bipolar-CMOS-DMOS (BCDMOS) process, the regulator operates over a wide frequency range from 7.018 kHz to 6.674 MHz at a 2 V reference output. It achieves a transient response of approximately 138 & micro;s for load current shifts from 100 nA to 10 & micro;A, with a maximum load current of 15 & micro;A. A load capacitor of 50 pF and a dropout voltage of 500 mV were utilized. The quiescent current is approximately 112 nA when active in low-power mode and about 2 nA when inactive with only power supply applied.

키워드