A 94.4% Peak Efficiency Coupled-Inductor Hybrid Step-Up Converter With Load-Independent Output Voltage Ripple

This article introduces a coupled-inductor hybrid step-up converter (CIHSUC) designed for low-ripple power supply applications in battery-operated devices. The CIHSUC combines the advantages of both a boost converter and a KY converter by proposing a novel hybrid converter topology that connects the input and output terminals of the converter in series with the coupled-inductor, resulting in a high conversion ratio (CR) and load-independent ultra-low output voltage ripple. By utilizing a coupled inductor instead of two discrete inductors, the CIHSUC further reduces inductor current ripple, output voltage ripple, and system size. Furthermore, $V^{2}I_{\text {C}}$ adaptive off-time (AOT) control method is proposed to enhance the transient response and loop stability. Fabricated in a $0.18~\mu $ m BCD process, the converter achieves a peak efficiency of 94.4% at ${V_{\text {IN}}} =5$ V, ${V_{\text {O}}} =12$ V and ${I_{\text {Load}}} =300$ mA. Additionally, the measured output voltage ripple remains below 20 mV within the input range of 2–5 V and the output range of 5–15 V, representing up to a $6.6\times $ reduction compared to the theoretical optimum of a conventional boost converter.