A Fast, Sigma–Delta $(\Sigma \Delta)$ Boost DC–DC Converter Tolerant to Wide <i>LC</i> Filter Variations

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Power supplies in portable electronics must adapt to their highly integrated environments and, more intrinsically, respond quickly to fast load dumps. However, frequency compensation must cater to the worst case design <emphasis emphasistype="italic">LC</emphasis> combination, be it because of tolerance and/or variable design targets, limiting speed and regulation performance to the worst-case scenario, even under best case conditions. Sigma–delta (<formula formulatype="inline"><tex>$\Sigma \Delta$</tex></formula>) control, which addresses this issue in buck converters, has not been able to concurrently achieve both high speed and wide <emphasis emphasistype="italic">LC</emphasis> compliance in boost converters. This paper presents a dual-loop <formula formulatype="inline"> <tex>$\Sigma \Delta$</tex></formula> boost converter whose prototype <formula formulatype="inline"><tex>$(5 \pm 5\hbox{\%}\ {\hbox {V} }, 1 {\hbox {A}})$</tex> </formula> was 20% faster and at least nine times more <emphasis emphasistype="italic">LC</emphasis> compliant than its leading current-mode PWM counterpart, and this without a compensation circuit. Light load efficiency, intrinsic for battery life, was also better (2% higher at 0.5 W, 600 kHz) because of lower switching losses. The tradeoffs for these benefits were higher output ripple voltage <formula formulatype="inline"> <tex>$(5 {\hbox {V} }\ \pm 1.7{\%})$</tex></formula> and lower high load efficiency (less than 1.9% lower at 5W, 300 kHz). </para>