A Four-Phase Hybrid Step-Up/Down Converter With RMS Inductor Current Reduction and Delay-Based Zero-Current Detection

Abstract

In this letter, a four-phase hybrid step-up/step-down dc–dc converter with a delay-based zero-current detector (ZCD) is proposed. The proposed power stage operates in step-up or step-down mode depending on the target output voltage. It utilizes hybrid switched-inductor-capacitor and dual-path topologies with multiphase operation to reduce conduction loss due to the dc resistance of the inductor by reducing the rms inductor current ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_L</i> ). The delay-based ZCD determines the zero-current point of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_L</i> with a five-bit binary signal to compensate for the propagation delay between the control and the output signals of the driver. The system is fabricated using 180-nm CMOS technology. The power density is 1.838 A/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , and the peak efficiency is measured at 89.49% and 86.83% in the step-down and step-up mode, respectively, with a load current range of up to 2 A.