Fully Integrated Low-Ripple Switched-Capacitor DC-DC Converter with Parallel Low-Dropout Regulator

Abstract

In this paper, we propose a fully integrated switched-capacitor DC-DC converter with low ripple and fast transient response for portable low-power electronic devices. The proposed converter reduces the output ripple by filtering the control ripple via combining a low-dropout regulator with a main switched-capacitor DC-DC converter with a four-bit digital capacitance modulation control. In addition, the four-phase interleaved technique applied to the main converter reduces the switching ripple. The proposed converter provides an output voltage ranging from 1.2 to 1.5 V from a 3.3 V supply. Its peak efficiency reaches 73% with ripple voltages below 55 mV over the entire output power range. The transient response time for a load current variation from 100 A to 50 mA is measured to be 800 ns. Importantly, the converter chip, which is fabricated using 0.13 m complementary metal-oxide-semiconductor (CMOS) technology, has a size of 2.04 mm(2). We believe that our approach can contribute to advancements in power sources for applications such as wearable electronics and the Internet of Things.