Load-Balance-Independent High Efficiency Single-Inductor Multiple-Output (SIMO) DC-DC Converters

Abstract

A single-inductor multiple-output (SIMO) DC-DC converter providing buck and boost outputs with a new switching sequence is presented. In the proposed switching sequence, which does not require any additional blocks, input energy is delivered to outputs continuously by flowing current through the inductor, which leads to high conversion efficiency regardless of the balance between the buck and boost output loads. Furthermore, instead of multiple output loop compensation, only the freewheeling current feedback loop is compensated, which minimizes the number of off-chip components and nullifies the need for the equivalent series resistance (ESR) of the output capacitor for loop compensation. Therefore, power conversion efficiency and output voltage ripples can be improved and minimized, respectively. Implemented in a 0.35-mu m CMOS, the proposed SIMO DC-DC converter achieves high conversion efficiency regardless of the load balance between the two outputs with maximum efficiency reaching up to 82% under heavy loads.