A High Efficiency and Fast Transient Digital Low-Dropout Assisted Switched-Capacitor Converter for EMI-Free Internet of Everything (IoE) Systems

Abstract

State-of-the-art closed-loop switched-capacitor (SC) designs usually regulate the output voltage by pulse frequency modulation (PFM) with the disadvantage of large electromagnetic interference (EMI). It may cause the failure of the Internet of Everything (IoE) devices. This paper proposes the hybrid digital low drop-out (DLDO) SC converter with a constant switching pulse width modulation (PWM) control for low EMI. Besides, the analog-to-digital current conversion provided by the DLDO due to its fast transient response can predict the desired ratio for the SC and reduce the dip voltage at the same time. The handshaking technique achieves smooth transition in the hybrid architecture. Experimental results show peak efficiency of 85% (closed-loop) and 95% (open loop) since the power converter has fast transient response by the DLDO prediction and reduction of switching power loss. Accurate fine tune operation by the DLDO and smooth handshaking improve load regulation from 49mV to 3mV and undershoot from 263mV to 93mV with a reduced recovery time of 200ns.