A Charge-Pump-based Digital LDO Employing an AC-Coupled High-Z Feedback Loop Towards a sub-4fs FoM and a 105,000x Stable Dynamic Current Range

This paper presents an event-driven charge-pumpbased digital LDO (DLDO) with an AC-coupled high-Z (ACHZ) feedback loop. The proposed DLDO responses in less than a clock cycle during load transients, achieving response and settling times of 6.9ns and 65ns, respectively, all at a 4.9μA quiescent current for a sub-4fs FoM. Thanks to the fine-tuning, sub-Vt detecting, overflow current suppressing, and g
_m
-adjusting weighted-chargepump-based design, the ripple is measured to be <;15mV, and a 105,000x stable load range (1μA to 105mA) is obtained in a 65nm prototype.