A 94.5%-Peak-Efficiency Dual-Path Single-Inductor Dual-Output Converter with Reduced Inductor Current and Output Voltage Ripple

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Abstract
Single-inductor multiple-output (SIMO) converters are highly favored in cost- and size-constrained battery-powered electronic devices because they reduce the need for multiple bulky inductors. However, as loading demands increase, conventional SIMO converters [1]–[2] face several challenges. First, compared with single-output buck converters, efficiency of SIMO converters is compromised due to increased loss introduced by the additional switches. Second, the inductor must have a high saturation current, which requires a larger volume, to handle loading currents up to several amps, thereby degrading power density. Third, discontinuous current delivery to the outputs results in large output ripples and high di/dt voltage spikes at the energy distribution switches, raising reliability concerns. While multi-level topology [3]–[5] or DSD topology [6] can alleviate these issues by reducing the voltage across the inductor and thus minimizing the inductor current ripple, the DC current through the inductor remains large. On the other hand, dual-path topologies have been extensively investigated in single-output converters due to their ability to reduce inductor current [7]–[8]. The dual-path technique utilizes the inductor to charge both the flying capacitor and the output capacitor in series during one phase, enabling the flying capacitor and the inductor to simultaneously charge the output during another phase. This approach become even more attractive when extended to SIMO converters [9], as it ensures more continuous current delivery to the outputs due to the charge provided the flying capacitor. However, the hybrid SIMO converter in [9] can only operate under balanced load conditions and support the voltage conversion ratio (VCR) of 0~0.5, limiting its applicability for multi-output applications.

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