A 5-to-1V DLDO-Hybrid-Sigma Converter Achieving Fast Transient for High-Density Power Delivery

A hybrid sigma converter integrated with a digital low dropout (DLDO) regulator is presented in this paper and designed for high-density power delivery applications. The proposed converter employs an input-series and output-parallel (ISOP) topology, combining a high-side hybrid converter for high power efficiency and a low-side DLDO for rapid transient regulation. An auxiliary control loop minimizes the DLDO’s dropout voltage across wide input and output voltage ranges, eliminating efficiency degradation under non-optimal operating conditions. The converter achieves a peak efficiency of 92%, with a system power density of $101.3 \mathrm{~W} / \mathrm{cm}^{3}$. A $1.6 \mu$ s response time and $\mathbf{3 6 m V}$ voltage droop are achieved with a $\mathbf{2 A}$ load transient.