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Authors Carlos J. Solis; Gabriel A. Rincon-Mora
Page pp.321-326
ISSN 1598-1657
Keywords Design ; analysis ; stability ; high bandwidth ; dc?dc power supply ; and hysteretic current-mode control ;
Abstract Emerging wireless microsystems rely on tiny batteries and intermittent energy-harvesting sources for energy and power. To sense, process, and report numerous events across extended periods, they often idle and wake to full-power conditions. Their power supplies must therefore be compact and efficient and respond quickly to sudden wide load changes. Hysteretic current-mode switched-inductor dc?dc converters are good for this application space because they are compact, efficient, and fast. Although also widely stable, they are nevertheless subject to instabilities. This paper explains how input and output voltages and load dumps limit stability, and as a result, bandwidth and response time. Measurements of a 200-mA, 1-V, 0.18-μm CMOS hysteretic current-mode buck with 95% peak power-conversion efficiency show how increasing the load-dump step by 140 mA and decreasing the input voltage by 400 mV compromise stability.