PLL-based charge control scheme for SIMO buck DC-DC converter

Abstract

This paper presents a phase-locking-loop-based (PLL-based) charge control scheme to enhance the cross regulation (CR) performance of charge-controlled SIMO Buck DC-DC without freewheel period. By combining PLL structure with the traditional charge control scheme, each channel could be regulated by an independent charge control loop. Moreover, a gain-adapted charge pump (GACP) technique is applied for the stability in multi-load condition. The multi-loop stability and CR expressions are derivated to improve their relative performance. Experimental results show that the proposed scheme can achieve worst-case CR of 0.052mV/mA in 384mA load transient, and 0.038mV/mA CR in 150mA load transient with at least 43.2% improvement above the existing charge control schemes.