A Fully Integrated Switched-Capacitor Voltage Regulator With Switching-Aware Ripple Injection LDO Achieving up to 77% Ripple Reduction

This letter presents a fully integrated switched-capacitor voltage regulator (SCVR) assisted by an ultralow-dropout (ULDO) regulator, featuring a switching-aware ripple injection (SARI) technique. The SARI replicates the SCVR ripple by leveraging its control signals, enabling the ULDO to effectively suppress the output voltage ripple even under a full-load condition. The SCVR employs a parasitic charge redistribution along with an ultralow dropout voltage of less than 60 mV in the ULDO, achieving a peak power efficiency of 80.5%. A prototype of the SCVR was fabricated using a 28-nm CMOS process, converting an input voltage of 1.8 V to a regulated output of 0.8 V. Measurement results demonstrate that the ULDO, when combined with SARI, successfully reduces the SCVR’s output voltage ripple to below 4.5 mV at a full load of 40 mA, achieving up to 77.9% ripple reduction.