Switched inductor capacitor buck converter with >85% power efficiency in 100uA-to-300mA loads using a bang-bang zero-current detector

As portable devices have been widely spread in nowadays, PMIC with a high efficiency in wide load range have been the main design focus. In this paper, an accurate bang-bang zero-current detector to prevent reverse inductor current and a triple mode switched inductor-capacitor buck converter to extend load range are presented. The proposed converter sustains minimum power conversion efficiency of 85% in the output load range from 100uA to 300mA. The chip was fabricated in a 0.18um CMOS process.

I. Introduction

Battery powered portable devices are becoming common in our daily lives. Also, portable systems usually require long working lifetimes with limited battery sources, and emerging internet-of-things (IoT) systems, such as wearable devices and home automation, mainly operate under idle and/or light load conditions. Therefore, the need for power management IC (PMIC), which guarantees high efficiency in a wide load range, especially under light load conditions, is increasing.