Small Saturating Inductors for More Compact Switching Power Supplies

Other than by reducing power, extending battery life in portable microelectronics amounts to increasing power efficiency, which when coupled with accuracy, translates to increasing filter inductance. The problem with higher inductances is magnetic cores require more space to prevent the onset of saturation, so accuracy and efficiency (via their need for bulky inductors) hamper the miniaturization benefits gained from chip integration. This paper illustrates the time-domain and efficiency effects of inductor saturation in switched-inductor dc-dc converters and shows how they can accommodate saturation (with up to 65% reduction in inductance) with minimal impact on battery life and accuracy. Extending the useful range of an inductor in this fashion not only reduces PCB area and volume to a fraction (e.g., 30–50%) of what an otherwise larger unsaturated inductor would require but also helps bridge the integration gap that enables practical system-on-chip (SoC) implementations.