11.9 A Compact 12V-to-1V 91.8% Peak Efficiency Hybrid Resonant Switched-Capacitor Parallel Inductor (ReSC-PL) Buck Converter

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High power density, high efficiency, and high voltage conversion ratio (VCR) DC-DC converters are in great demand for portable devices and autonomous robots. The double-step-down (DSD) converter and its variants are promising solutions for their reduced voltage stress on the power transistors, extended duty-cycle (D), and higher equivalent switching frequency [1–4]. However, all these topologies suffer from the trade-off between efficiency and current density, since all the output current <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I₀</tex> flows through the power inductors, we have to either use bulky inductors for high efficiency or use small inductors for high current density. To deal with this, [5] proposed an always-dual-path (ADP) hybrid converter that can reduce the inductor current <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IL</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5I₀</tex> , but at the cost of a larger inductor current ripple <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Δ IL</tex> ' Besides, [6] proposed a hybrid switched-capacitor (SC)-parallel-inductor (CPL) buck converter that reduces <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IL</tex> without enlarging <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Δ IL</tex> , achieving high efficiency and high current density simultaneously. Nevertheless, such CPL-Buck converter only deals with a 1-cell battery input, and is not suitable for high VCR conversion, e.g., 12V-to-1V. Because its inductor current reduction effect highly depends on D, and thus its benefits drop heavily at a high VCR. In this work, we propose a hybrid resonant SC parallel inductor (ReSC-PL) buck converter that can always effectively reduce <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IL</tex> to below <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5 I₀~ 0.67I₀</tex> for high VCRs ranging from 10 to 20. <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IL</tex>