An optimization method for PLL-based charge control SIMO Buck DC-DC

The PLL-based charge control scheme is optimized and implemented in a single-inductor multiple-output (SIMO) Buck DC-DC in this paper. In order to decrease cross regulation (CR) during heavy load transient, the gain adaptive charge pump (GACP) is optimized to speed up the regulation of inductor current, and the current loop off-time (CLOT) control is introduced to prevent the PLL-based structure from frequency unlock. The proposed SIMO is designed in a 0.18 mu m standard CMOS process. Experimental results show that the worst CR performance is 0.026 mV/mA, which is a 50% improvement of PLL-based charge control scheme and 61.19% advantage above the existing charge-controlled SIMO.