A low-ripple efficiency-improvement switched-capacitor boost converter for battery-supplied low-noise applications

Abstract

This paper presents a on-demand switch-on modulation (DSM) switched-capacitor charge pump (SCCP) for battery-supplied low-noise Internet-of-Things (IoT) devices. In the proposed technique, SCCP consists of two same submodules achieving 1.5X and 2X conversion ratios and the charge–discharge switches in CP core are split into parallel structures with binary-sized unit switches to adjust the charging current on-demand to improve the power conversion efficiency. To further reduce the output ripple under all load conditions, a novel two-step pulse skip modulation (PSM) ripple suppression technique is designed. The startup ripple is minimized by the proposed one-by-one startup circuit to reduce system power loss. The proposed DSM SCCP was fabricated using a 55 nm CMOS process to boost a single battery voltage (from 1.2 V to 1.5 V) up to 1.95 V. With another on-chip implemented low-dropout (LDO) regulator, a low-noise output of 1.73 V can be obtained by the low noise processing boost converter circuit. The measurement results demonstrate that the minimum CP ripple of 9.5 to 15.5 mV is achieved for 0 to 10 mA system load, respectively. Finally, a peak power conversion efficiency of 94.2% and 84.8% is realized for the proposed DSM SCCP and low noise processing boost converter circuit, respectively.